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Smit Oletha review: just a Z4 with a mighty price tag? Far from it

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Smit Oletha review: just a Z4 with a mighty price tag? Far from it | Top Gear

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No this isn’t a Z8 hardtop. It’s something much more specialised – a greatest hits of BMW tribute

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Smit Oletha review: just a Z4 with a mighty price tag? Far from it

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What is it? It’s not what you think it is, this car. I reckon you’re looking at it and thinking ‘what have they done to a BMW Z8?’ But all is not as it seems here. This is not a BMW Z8 coupe so much as a greatest hits of BMW’s parts bin. It’s called the Smit Oletha and it’s the brainchild of two engineering-obsessed brothers from California, Willem and Kaess Smit.

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No this isn’t a Z8 hardtop. It’s something much more specialised – a greatest hits of BMW tribute

# data.attributes.metatag[].attributes.content
Smit Oletha review: just a Z4 with a mighty price tag? Far from it

# data.attributes.metatag[].attributes.content
Smit Oletha review: just a Z4 with a mighty price tag? Far from it

# data.attributes.metatag[].attributes.content
No this isn’t a Z8 hardtop. It’s something much more specialised – a greatest hits of BMW tribute

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No this isn’t a Z8 hardtop. It’s something much more specialised – a greatest hits of BMW tribute

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What is it?It’s not what you think it is

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this car. I reckon you’re looking at it and thinking ‘what have they done to a BMW Z8?’ But all is not as it seems here. This is not a BMW Z8 coupe so much as a greatest hits of BMW’s parts bin. It’s called the Smit Oletha and it’s the brainchild of two engineering-obsessed brothers from California

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Willem and Kaess Smit. Both have mechanical engineering backgrounds

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one in aerospace and advanced composites

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the other in automotive with stints at both Tesla and Singer.I’m guessing the latter was useful?Yeah

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although rather than Porsche both brothers were BMW disciples from way back (so would you be if your old man sped about in an E39 M5). And

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they weren’t happy with the direction the car industry generally

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had taken recently. So they decided to create their dream BMW.You wait ages for one BMW restomod to come along and suddenly two turn up at once!You’re right

# data.attributes.metatag[].attributes.content.reviewBody[]
albeit with very different stated aims. Two weeks ago I reviewed the BMW E30 M3 Enhanced and Evolved by Redux. An extensive and sympathetic update to an existing E30

# data.attributes.metatag[].attributes.content.reviewBody[]
it wants nothing more than to be the best E30 M3 it can be.This is at the other end of the scale completely. It recreates a car that never was. Every good restomod needs to tell a story and the Smit isn’t putting its own spin on anything BMW has done before

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but instead imagines a world where BMW decided to build a rival to the 996-generation Porsche 911 GT3.Nothing like aiming for the top

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is there? Where have they started?With a BMW Z4.Come again?The Oletha takes its chassis

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basic suspension design and steering from the E86 BMW Z4 coupe that was built from 2006-2008. Sounds like a peculiar starting point when the intended end point costs several hundred thousand dollars

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but there is method in this madness. For starters

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that Z4 coupe had a very stiff chassis (a legacy of being a roadster first

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it’s literally three times stiffer than the BMW Z8. But has almost exactly the same body measurements and proportions. Now

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it was never a GT3 rival. It was a muscle car

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all woofly exhaust and thumping torque delivery. It wouldn’t have been the ideal starting point from which to create an incisive and immediate driver’s car.OK

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I’m coming round to it – I’m assuming it uses the famed 3.2-litre straight six?No. That’s something Smit is discussing for subsequent versions

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but this one uses something much more bespoke. It starts out as the 4.0-litre V8 from the E92 M3

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but is then treated to a load of mods that make it more akin to the S65B44 4.4-litre V8 fitted to the legendary M3 GTS. Like that it uses a longer stroke to get the extra capacity

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but almost all moving parts are new: crankshaft

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valve springs etc.The crucial numbers are these: 450bhp

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500rpm. All that goes to the rear wheels alone via a ZF six-speed manual taken from the E92 M3. There’s a mechanical LSD

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AP Racing brakes and forged monoblock wheels – all the raw ingredients necessary to develop a GT3 rival

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then.Who designed it?The brothers themselves. Not bad for a pair of engineers

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huh? I particularly like the line that runs from the top of the front wheel and pinches to a needlepoint at the door handle. Not sure about those in silver

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but that’s a matter of spec. All the body panels are carbon fibre (like the wheels

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sourced from a British supplier). The panel fit and finish

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the sheer quality evident around the car

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is exceptional.Smit drew inspiration not only from the Z8

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the 507 of 1956. The moustache grille is the most recognisable feature

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but for better or worse it does soften the front end. I’d argue a GT3 rival needs a more assertive nose. But then I’m not sure the GT3 comparo is quite right in the first place. More on that in a bit.There’s clever stuff here though. This is a geek point

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but one of the most expensive things to develop for a car is its glasshouse. No big glass manufacturer wants to create bespoke glass for only a few dozen cars. End result? Glass costs a fortune. So here it’s carried over directly from the Z4 coupe. You’d never guess. I spent all day around the car and not once did I put two and two together. It’s beautifully integrated.But you can tell it’s a Z4 inside

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can’t you?Depends how familiar you are with the Z4. You and I might recognise it immediately

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but the paddle-shaped aluminium slab that forms the dash is actually a lovely bit of cabin architecture. What slightly lets it down is the black plastic hifi and air vent panel.And that’s true elsewhere. Although the cockpit has a clean aesthetic

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doesn’t have enough surprise and delight features

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doesn’t have the richness of texture and trim it deserves. There’s also an odd juxtaposition between the period-inspired bodywork and more contemporary cabin. But I wouldn’t call it a clash

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more a slightly offbeat rhythm.But: the driving position is great

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the seats are wrapped in beautiful leather

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there are three pedals in the footwell and before you even start it

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the Oletha (pronounce it O-lee-tha) feels compact and together.But all I’m seeing so far is a rebodied Z4 with a stonking engine.So was I. I admired the work that had clearly gone into it

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was impressed by the skill and ability the brothers had put into it

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but wasn’t sure what the end result would be.And then I started the engine. In my head it was going to be one of those zingy

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frenetic V8s. No. It fires into life with a bassy American throb. Not attention seeking

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just purposeful. I slot first. The clutch isn’t the monster I feared and that stubby gearshift is so precise and positive. It likes to be fed all the way into a gear though

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not flicked negligently about. But that’s right – it suits the car.And once you get into third

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you can leave it alone. Third has more than enough reach and drive to accomplish everything. You touch the throttle at tickover and it’s off

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lunging forwards. You let it keep going and the noise hardens

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intensifies. Doesn’t feel or act like a lazy V8 now

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feels like the internals have shaken excess flab loose and are getting motorsport serious. Masses of speed

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all building to a crescendo. So you predict the limiter and begin to reach for the gearlever to shift-up. And as you do you glance at the rev counter. And it’s only just cresting 6

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500rpm to play with. Wha-hey! And that last section is just so special

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so screamingly intense. It’s not the speed it gains so much as how it makes you feel

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the sense of barely tamed beast thrashing away up front. What a drivetrain

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so multi-faceted and rewarding. So responsive

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confident in itself and well-mannered. Finding opportunities to use it is the trickiest bit.What are the performance figures?Smit hasn’t measured them

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and since it’s a manual they won’t be anything to write home about by modern standards. Around 4.0secs to 60mph

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I’d guess. But this is about performance on a wider scale. Think artistic rather than mathematic. Because it’s a captivating way to get about: the view down the long bonnet that unfurls as you exit a corner

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the intensity and immediacy of the engine response and power delivery

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the sense the chassis is only just coping with that V8 trying to burst out of the bonnet (have a look in the engine bay and you’ll see how close that is to the truth).It’s not a big car and weighs only 1

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giving it a power to weight ratio of 320bhp/tonne. About the same as a current M5. Yep

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but with a viscerality that’s a world away. It powers down straights

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hurls itself forwards in that relentless crescendo that only large capacity naturally aspirated engines in small frames can. Makes a noise to summon the gods and rouses whole hillsides. And that’s why it reminds me not of a 911 GT3

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but if you drove this around Goodwood or Le Mans

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Cobras and DB4 GTs would come to mind.Can it handle corners?This is where we can bring the GT3 back into play. Let’s start here: it doesn’t have the steering clarity and detail of an early GT3

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nor the tenacity and attacking nature – although a large part of that is because you sit further back in the chassis. But it does a job today that no BMW did back then. It’s emphatically not a GT

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urging you on. It’s most like an Aston Vantage in having that crispness while still being front engined. It dives into corners eagerly

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grips hard and never lets go. It’s really nicely balanced too.Adjustable suspension means owners will be able to play with the set-up. I drove it in a ‘fast road’ state that gave me huge confidence in the front end

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little roll but enough to let you know the car was working. It was only through bumpy corners that I got a bit of diagonal porpoising as front and rear levered against each other momentarily. The mechanical differential manages traction beautifully

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so you’re going plenty hard enough before the ESP gets involved.What about cruising? Does it relax?The engine note dies away and the car does lose tension and feel calm. Just bear in mind you’re not going far between fill-ups. That V8 is a thirsty beast and the Z4's 55-litre fuel tank is hardly enormous. The Smit brothers have actually engineered their own pop-up spoiler to aid high speed stability. Activated manually by a switch

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modelling shows it reduces rear-end lift from 90kg to less than 30kg at 124mph. Most impressive thing about that? That Smit know the figures and have done the computing and calculations. This is a thoroughly engineered and thought through car. It’s going to be expensive isn’t it!Yes it is

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and there’s an easy line here which doesn’t make comfortable reading for Smit: this is a $450

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000) BMW Z4. And inside there are elements that don’t match up to that.But then there are elements you’ll never see that have received astonishing care. Let me give you an example. The V8 wasn’t an easy fit. The exhaust manifolds didn’t fit in the Z4 engine bay

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interfering with chassis rails and steering column. It wasn’t just a question of designing new manifolds

# data.attributes.metatag[].attributes.content.reviewBody[]
but the whole packaging of the engine bay. They went through 25 iterations. They’ve ended up having to pass the steering through the exhaust manifold. The tolerances are only 5mm

# data.attributes.metatag[].attributes.content.reviewBody[]
which meant that Smit had to design and engineer new engine mounts and have them 3D printed in stainless steel. But those work alongside the original engine mounts so you don’t get excess vibration. And they’ve designed it so they can build right-hand drive cars if the demand is there. That’s called going the extra mile. And it’s everywhere you look on the Oletha. So to dismiss this car as an overpriced Z4 with a slightly iffy cabin is to sell it hugely short.They have a stated aim to build no more than 100

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but appreciate that’s a long shot. A few dozen

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then. But beyond that the brothers deserve to build a reputation. If they can turn a Z4 into a convincing facsimile of GT3-inspired Z8

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No this isn’t a Z8 hardtop. It’s something much more specialised – a greatest hits of BMW tribute

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What is it?

It’s not what you think it is, this car. I reckon you’re looking at it and thinking ‘what have they done to a BMW Z8?’ But all is not as it seems here. This is not a BMW Z8 coupe so much as a greatest hits of BMW’s parts bin. It’s called the Smit Oletha and it’s the brainchild of two engineering-obsessed brothers from California, Willem and Kaess Smit. Both have mechanical engineering backgrounds, one in aerospace and advanced composites, the other in automotive with stints at both Tesla and Singer.

I’m guessing the latter was useful?

Yeah, although rather than Porsche both brothers were BMW disciples from way back (so would you be if your old man sped about in an E39 M5). And, like so many of us, they weren’t happy with the direction the car industry generally, and BMW specifically, had taken recently. So they decided to create their dream BMW.

You wait ages for one BMW restomod to come along and suddenly two turn up at once!

You’re right, albeit with very different stated aims. Two weeks ago I reviewed the BMW E30 M3 Enhanced and Evolved by Redux. An extensive and sympathetic update to an existing E30, it wants nothing more than to be the best E30 M3 it can be.

This is at the other end of the scale completely. It recreates a car that never was. Every good restomod needs to tell a story and the Smit isn’t putting its own spin on anything BMW has done before, but instead imagines a world where BMW decided to build a rival to the 996-generation Porsche 911 GT3.

Nothing like aiming for the top, is there? Where have they started?

With a BMW Z4.

Come again?

The Oletha takes its chassis, basic suspension design and steering from the E86 BMW Z4 coupe that was built from 2006-2008. Sounds like a peculiar starting point when the intended end point costs several hundred thousand dollars, but there is method in this madness. For starters, that Z4 coupe had a very stiff chassis (a legacy of being a roadster first, then having a roof added). At 32,000Nm per degree, it’s literally three times stiffer than the BMW Z8. But has almost exactly the same body measurements and proportions.

Now, great though the Z8 was, it was never a GT3 rival. It was a muscle car, all woofly exhaust and thumping torque delivery. It wouldn’t have been the ideal starting point from which to create an incisive and immediate driver’s car.

OK, I’m coming round to it – I’m assuming it uses the famed 3.2-litre straight six?

No. That’s something Smit is discussing for subsequent versions, but this one uses something much more bespoke. It starts out as the 4.0-litre V8 from the E92 M3, but is then treated to a load of mods that make it more akin to the S65B44 4.4-litre V8 fitted to the legendary M3 GTS. Like that it uses a longer stroke to get the extra capacity, but almost all moving parts are new: crankshaft, pistons, conrod, cams, valve springs etc.

The crucial numbers are these: 450bhp, 340lb ft and 8,500rpm. All that goes to the rear wheels alone via a ZF six-speed manual taken from the E92 M3. There’s a mechanical LSD, two-way adjustable KW suspension, AP Racing brakes and forged monoblock wheels – all the raw ingredients necessary to develop a GT3 rival, then.

Who designed it?

The brothers themselves. Not bad for a pair of engineers, huh? I particularly like the line that runs from the top of the front wheel and pinches to a needlepoint at the door handle. Not sure about those in silver, but that’s a matter of spec. All the body panels are carbon fibre (like the wheels, sourced from a British supplier). The panel fit and finish, the tightness of the gaps, the sheer quality evident around the car, is exceptional.

Smit drew inspiration not only from the Z8, but the car that inspired that, the 507 of 1956. The moustache grille is the most recognisable feature, but for better or worse it does soften the front end. I’d argue a GT3 rival needs a more assertive nose. But then I’m not sure the GT3 comparo is quite right in the first place. More on that in a bit.

There’s clever stuff here though. This is a geek point, but one of the most expensive things to develop for a car is its glasshouse. No big glass manufacturer wants to create bespoke glass for only a few dozen cars. End result? Glass costs a fortune. So here it’s carried over directly from the Z4 coupe. You’d never guess. I spent all day around the car and not once did I put two and two together. It’s beautifully integrated.

But you can tell it’s a Z4 inside, can’t you?

Depends how familiar you are with the Z4. You and I might recognise it immediately, but the paddle-shaped aluminium slab that forms the dash is actually a lovely bit of cabin architecture. What slightly lets it down is the black plastic hifi and air vent panel.

And that’s true elsewhere. Although the cockpit has a clean aesthetic, free from distractions, it’s not quite glorious enough, doesn’t have enough surprise and delight features, doesn’t have the richness of texture and trim it deserves. There’s also an odd juxtaposition between the period-inspired bodywork and more contemporary cabin. But I wouldn’t call it a clash, more a slightly offbeat rhythm.

But: the driving position is great, the seats are wrapped in beautiful leather, there are three pedals in the footwell and before you even start it, the Oletha (pronounce it O-lee-tha) feels compact and together.

But all I’m seeing so far is a rebodied Z4 with a stonking engine.

So was I. I admired the work that had clearly gone into it, was impressed by the skill and ability the brothers had put into it, but wasn’t sure what the end result would be.

And then I started the engine. In my head it was going to be one of those zingy, high-idling, frenetic V8s. No. It fires into life with a bassy American throb. Not attention seeking, just purposeful. I slot first. The clutch isn’t the monster I feared and that stubby gearshift is so precise and positive. It likes to be fed all the way into a gear though, not flicked negligently about. But that’s right – it suits the car.

And once you get into third, you can leave it alone. Third has more than enough reach and drive to accomplish everything. You touch the throttle at tickover and it’s off, greedily gathering revs, lunging forwards. You let it keep going and the noise hardens, sharpens, intensifies. Doesn’t feel or act like a lazy V8 now, feels like the internals have shaken excess flab loose and are getting motorsport serious. Masses of speed, even more drama, all building to a crescendo. So you predict the limiter and begin to reach for the gearlever to shift-up. And as you do you glance at the rev counter. And it’s only just cresting 6,000rpm.

Yep, you’ve still got 2,500rpm to play with. Wha-hey! And that last section is just so special, so screamingly intense. It’s not the speed it gains so much as how it makes you feel, the vibrations through your chest, the sense of barely tamed beast thrashing away up front. What a drivetrain, so multi-faceted and rewarding. So responsive, endlessly enthralling, confident in itself and well-mannered. Finding opportunities to use it is the trickiest bit.

What are the performance figures?

Smit hasn’t measured them, and since it’s a manual they won’t be anything to write home about by modern standards. Around 4.0secs to 60mph, I’d guess. But this is about performance on a wider scale. Think artistic rather than mathematic. Because it’s a captivating way to get about: the view down the long bonnet that unfurls as you exit a corner, the intensity and immediacy of the engine response and power delivery, the sense the chassis is only just coping with that V8 trying to burst out of the bonnet (have a look in the engine bay and you’ll see how close that is to the truth).

It’s not a big car and weighs only 1,401kg, giving it a power to weight ratio of 320bhp/tonne. About the same as a current M5. Yep, that sort of speed, but with a viscerality that’s a world away. It powers down straights, hurls itself forwards in that relentless crescendo that only large capacity naturally aspirated engines in small frames can. Makes a noise to summon the gods and rouses whole hillsides. And that’s why it reminds me not of a 911 GT3, but of a Sixties GT racer. It’s a vibe, rather than a specific car, but if you drove this around Goodwood or Le Mans, I think E-Types, Cobras and DB4 GTs would come to mind.

Can it handle corners?

This is where we can bring the GT3 back into play. Let’s start here: it doesn’t have the steering clarity and detail of an early GT3, nor the tenacity and attacking nature – although a large part of that is because you sit further back in the chassis. But it does a job today that no BMW did back then. It’s emphatically not a GT, it doesn’t lazily waft about, but instead engages with you, urging you on. It’s most like an Aston Vantage in having that crispness while still being front engined. It dives into corners eagerly, grips hard and never lets go. It’s really nicely balanced too.

Adjustable suspension means owners will be able to play with the set-up. I drove it in a ‘fast road’ state that gave me huge confidence in the front end, little roll but enough to let you know the car was working. It was only through bumpy corners that I got a bit of diagonal porpoising as front and rear levered against each other momentarily. The mechanical differential manages traction beautifully, so you’re going plenty hard enough before the ESP gets involved.

What about cruising? Does it relax?

The engine note dies away and the car does lose tension and feel calm. Just bear in mind you’re not going far between fill-ups. That V8 is a thirsty beast and the Z4's 55-litre fuel tank is hardly enormous.

The Smit brothers have actually engineered their own pop-up spoiler to aid high speed stability. Activated manually by a switch, modelling shows it reduces rear-end lift from 90kg to less than 30kg at 124mph. Most impressive thing about that? That Smit know the figures and have done the computing and calculations. This is a thoroughly engineered and thought through car.

It’s going to be expensive isn’t it!

Yes it is, and there’s an easy line here which doesn’t make comfortable reading for Smit: this is a $450,000 (£335,000) BMW Z4. And inside there are elements that don’t match up to that.

But then there are elements you’ll never see that have received astonishing care. Let me give you an example. The V8 wasn’t an easy fit. The exhaust manifolds didn’t fit in the Z4 engine bay, interfering with chassis rails and steering column. It wasn’t just a question of designing new manifolds, but the whole packaging of the engine bay. They went through 25 iterations. They’ve ended up having to pass the steering through the exhaust manifold. The tolerances are only 5mm, which meant that Smit had to design and engineer new engine mounts and have them 3D printed in stainless steel. But those work alongside the original engine mounts so you don’t get excess vibration. And they’ve designed it so they can build right-hand drive cars if the demand is there. That’s called going the extra mile. And it’s everywhere you look on the Oletha. So to dismiss this car as an overpriced Z4 with a slightly iffy cabin is to sell it hugely short.

They have a stated aim to build no more than 100, but appreciate that’s a long shot. A few dozen, then. But beyond that the brothers deserve to build a reputation. If they can turn a Z4 into a convincing facsimile of GT3-inspired Z8, we can’t wait to see what they do next.

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What is it?

It’s not what you think it is, this car. I reckon you’re looking at it and thinking ‘what have they done to a BMW Z8?’ But all is not as it seems here. This is not a BMW Z8 coupe so much as a greatest hits of BMW’s parts bin. It’s called the Smit Oletha and it’s the brainchild of two engineering-obsessed brothers from California, Willem and Kaess Smit. Both have mechanical engineering backgrounds, one in aerospace and advanced composites, the other in automotive with stints at both Tesla and Singer.

I’m guessing the latter was useful?

Yeah, although rather than Porsche both brothers were BMW disciples from way back (so would you be if your old man sped about in an E39 M5). And, like so many of us, they weren’t happy with the direction the car industry generally, and BMW specifically, had taken recently. So they decided to create their dream BMW.

You wait ages for one BMW restomod to come along and suddenly two turn up at once!

You’re right, albeit with very different stated aims. Two weeks ago I reviewed the BMW E30 M3 Enhanced and Evolved by Redux. An extensive and sympathetic update to an existing E30, it wants nothing more than to be the best E30 M3 it can be.

This is at the other end of the scale completely. It recreates a car that never was. Every good restomod needs to tell a story and the Smit isn’t putting its own spin on anything BMW has done before, but instead imagines a world where BMW decided to build a rival to the 996-generation Porsche 911 GT3.

Nothing like aiming for the top, is there? Where have they started?

With a BMW Z4.

Come again?

The Oletha takes its chassis, basic suspension design and steering from the E86 BMW Z4 coupe that was built from 2006-2008. Sounds like a peculiar starting point when the intended end point costs several hundred thousand dollars, but there is method in this madness. For starters, that Z4 coupe had a very stiff chassis (a legacy of being a roadster first, then having a roof added). At 32,000Nm per degree, it’s literally three times stiffer than the BMW Z8. But has almost exactly the same body measurements and proportions.

Now, great though the Z8 was, it was never a GT3 rival. It was a muscle car, all woofly exhaust and thumping torque delivery. It wouldn’t have been the ideal starting point from which to create an incisive and immediate driver’s car.

OK, I’m coming round to it – I’m assuming it uses the famed 3.2-litre straight six?

No. That’s something Smit is discussing for subsequent versions, but this one uses something much more bespoke. It starts out as the 4.0-litre V8 from the E92 M3, but is then treated to a load of mods that make it more akin to the S65B44 4.4-litre V8 fitted to the legendary M3 GTS. Like that it uses a longer stroke to get the extra capacity, but almost all moving parts are new: crankshaft, pistons, conrod, cams, valve springs etc.

The crucial numbers are these: 450bhp, 340lb ft and 8,500rpm. All that goes to the rear wheels alone via a ZF six-speed manual taken from the E92 M3. There’s a mechanical LSD, two-way adjustable KW suspension, AP Racing brakes and forged monoblock wheels – all the raw ingredients necessary to develop a GT3 rival, then.

Who designed it?

The brothers themselves. Not bad for a pair of engineers, huh? I particularly like the line that runs from the top of the front wheel and pinches to a needlepoint at the door handle. Not sure about those in silver, but that’s a matter of spec. All the body panels are carbon fibre (like the wheels, sourced from a British supplier). The panel fit and finish, the tightness of the gaps, the sheer quality evident around the car, is exceptional.

Smit drew inspiration not only from the Z8, but the car that inspired that, the 507 of 1956. The moustache grille is the most recognisable feature, but for better or worse it does soften the front end. I’d argue a GT3 rival needs a more assertive nose. But then I’m not sure the GT3 comparo is quite right in the first place. More on that in a bit.

There’s clever stuff here though. This is a geek point, but one of the most expensive things to develop for a car is its glasshouse. No big glass manufacturer wants to create bespoke glass for only a few dozen cars. End result? Glass costs a fortune. So here it’s carried over directly from the Z4 coupe. You’d never guess. I spent all day around the car and not once did I put two and two together. It’s beautifully integrated.

But you can tell it’s a Z4 inside, can’t you?

Depends how familiar you are with the Z4. You and I might recognise it immediately, but the paddle-shaped aluminium slab that forms the dash is actually a lovely bit of cabin architecture. What slightly lets it down is the black plastic hifi and air vent panel.

And that’s true elsewhere. Although the cockpit has a clean aesthetic, free from distractions, it’s not quite glorious enough, doesn’t have enough surprise and delight features, doesn’t have the richness of texture and trim it deserves. There’s also an odd juxtaposition between the period-inspired bodywork and more contemporary cabin. But I wouldn’t call it a clash, more a slightly offbeat rhythm.

But: the driving position is great, the seats are wrapped in beautiful leather, there are three pedals in the footwell and before you even start it, the Oletha (pronounce it O-lee-tha) feels compact and together.

But all I’m seeing so far is a rebodied Z4 with a stonking engine.

So was I. I admired the work that had clearly gone into it, was impressed by the skill and ability the brothers had put into it, but wasn’t sure what the end result would be.

And then I started the engine. In my head it was going to be one of those zingy, high-idling, frenetic V8s. No. It fires into life with a bassy American throb. Not attention seeking, just purposeful. I slot first. The clutch isn’t the monster I feared and that stubby gearshift is so precise and positive. It likes to be fed all the way into a gear though, not flicked negligently about. But that’s right – it suits the car.

And once you get into third, you can leave it alone. Third has more than enough reach and drive to accomplish everything. You touch the throttle at tickover and it’s off, greedily gathering revs, lunging forwards. You let it keep going and the noise hardens, sharpens, intensifies. Doesn’t feel or act like a lazy V8 now, feels like the internals have shaken excess flab loose and are getting motorsport serious. Masses of speed, even more drama, all building to a crescendo. So you predict the limiter and begin to reach for the gearlever to shift-up. And as you do you glance at the rev counter. And it’s only just cresting 6,000rpm.

Yep, you’ve still got 2,500rpm to play with. Wha-hey! And that last section is just so special, so screamingly intense. It’s not the speed it gains so much as how it makes you feel, the vibrations through your chest, the sense of barely tamed beast thrashing away up front. What a drivetrain, so multi-faceted and rewarding. So responsive, endlessly enthralling, confident in itself and well-mannered. Finding opportunities to use it is the trickiest bit.

What are the performance figures?

Smit hasn’t measured them, and since it’s a manual they won’t be anything to write home about by modern standards. Around 4.0secs to 60mph, I’d guess. But this is about performance on a wider scale. Think artistic rather than mathematic. Because it’s a captivating way to get about: the view down the long bonnet that unfurls as you exit a corner, the intensity and immediacy of the engine response and power delivery, the sense the chassis is only just coping with that V8 trying to burst out of the bonnet (have a look in the engine bay and you’ll see how close that is to the truth).

It’s not a big car and weighs only 1,401kg, giving it a power to weight ratio of 320bhp/tonne. About the same as a current M5. Yep, that sort of speed, but with a viscerality that’s a world away. It powers down straights, hurls itself forwards in that relentless crescendo that only large capacity naturally aspirated engines in small frames can. Makes a noise to summon the gods and rouses whole hillsides. And that’s why it reminds me not of a 911 GT3, but of a Sixties GT racer. It’s a vibe, rather than a specific car, but if you drove this around Goodwood or Le Mans, I think E-Types, Cobras and DB4 GTs would come to mind.

Can it handle corners?

This is where we can bring the GT3 back into play. Let’s start here: it doesn’t have the steering clarity and detail of an early GT3, nor the tenacity and attacking nature – although a large part of that is because you sit further back in the chassis. But it does a job today that no BMW did back then. It’s emphatically not a GT, it doesn’t lazily waft about, but instead engages with you, urging you on. It’s most like an Aston Vantage in having that crispness while still being front engined. It dives into corners eagerly, grips hard and never lets go. It’s really nicely balanced too.

Adjustable suspension means owners will be able to play with the set-up. I drove it in a ‘fast road’ state that gave me huge confidence in the front end, little roll but enough to let you know the car was working. It was only through bumpy corners that I got a bit of diagonal porpoising as front and rear levered against each other momentarily. The mechanical differential manages traction beautifully, so you’re going plenty hard enough before the ESP gets involved.

What about cruising? Does it relax?

The engine note dies away and the car does lose tension and feel calm. Just bear in mind you’re not going far between fill-ups. That V8 is a thirsty beast and the Z4's 55-litre fuel tank is hardly enormous.

The Smit brothers have actually engineered their own pop-up spoiler to aid high speed stability. Activated manually by a switch, modelling shows it reduces rear-end lift from 90kg to less than 30kg at 124mph. Most impressive thing about that? That Smit know the figures and have done the computing and calculations. This is a thoroughly engineered and thought through car.

It’s going to be expensive isn’t it!

Yes it is, and there’s an easy line here which doesn’t make comfortable reading for Smit: this is a $450,000 (£335,000) BMW Z4. And inside there are elements that don’t match up to that.

But then there are elements you’ll never see that have received astonishing care. Let me give you an example. The V8 wasn’t an easy fit. The exhaust manifolds didn’t fit in the Z4 engine bay, interfering with chassis rails and steering column. It wasn’t just a question of designing new manifolds, but the whole packaging of the engine bay. They went through 25 iterations. They’ve ended up having to pass the steering through the exhaust manifold. The tolerances are only 5mm, which meant that Smit had to design and engineer new engine mounts and have them 3D printed in stainless steel. But those work alongside the original engine mounts so you don’t get excess vibration. And they’ve designed it so they can build right-hand drive cars if the demand is there. That’s called going the extra mile. And it’s everywhere you look on the Oletha. So to dismiss this car as an overpriced Z4 with a slightly iffy cabin is to sell it hugely short.

They have a stated aim to build no more than 100, but appreciate that’s a long shot. A few dozen, then. But beyond that the brothers deserve to build a reputation. If they can turn a Z4 into a convincing facsimile of GT3-inspired Z8, we can’t wait to see what they do next.