Head to head: Mercedes-AMG C63 S vs Alfa Romeo Giulia Quadrifoglio

This is 2023’s – sorry, I mean 2024’s – most controversial car. It was always going to be tough to replace the old C63 – TG magazine regulars should leaf back to 2017’s issue 300, when the V8 coupe nuked the new Audi RS5, Lexus RCF and BMW's mighty M4. We called it “one of the very best cars on sale today”. Replacing it with an engine half the size, inspired by one of the most lambasted hypercar launches in history? Baby and bathwater, binned.

Photography: Jonny Fleetwood

You’d think after the debacle of the AMG One, Mercedes engineers might fancy a day off. What they did instead was yank the world’s most powerful street legal 4cyl engine out of the A45 where it was busily making an already silly 418bhp, and stuff an electric motor into its watermelon sized turbocharger. Satisfied they’d eradicated lag and bumped output to a record breaking 469bhp from 1991cc, they hoiked a 6.1kWh battery into the boot to power it. And while they were under there with the socket set and soldering iron, they jammed a 200bhp electric motor into the rear differential.

This allows the C63 to travel around six miles on battery power alone. It’ll actually heave its way to motorway speeds as an EV, but think of it more as a ‘quiet getaway’ mode. When both power sources are maxed, they combine for 671bhp. Welcome to 2024, where a factory C-Class has more power than a Ferrari Enzo. And weighs 2.1 tonnes.

By an uncanny coincidence, the lesser spotted C63 landed within days of BMW announcing a facelift of its touchstone M3, and deleting all demonstrators from its UK fleet. Instead, we’ve teed up something a little less... German.

The Alfa Romeo Giulia Quadrifoglio might be beyond its ninth birthday but it still looks sensational. Slammed seductively onto its teledial rims, it’s a quite beautiful slice of saloon car design – just the right amount of intent and malevolence. Next to it, the C63 is all attitude up front but meek in the rear. AMG’s bolstered the front track by 76mm but the slab-sided flanks spoil the effect. It’s almost as though the car narrows toward the rear, like a whale. Its predecessor’s confident stance has been lost, and no one’s fooled by the dummy exhaust outlets or fake side vents.

And this is the new Alfa, by the way. This year Giulias sport refreshed LED headlights and a 10bhp power hike from the Ferrari derived 2.9-litre bi-turbo V6. These days it sends 513bhp to a mechanical rear differential, in place of an electronically controlled one that was fragile on track. Inside, delectable gloss carbon-fibre trim has been replaced by grotesque matte weave from your nan’s shopping basket. Apple CarPlay mercifully arrived in the dated infotainment a while ago. Such miniscule changes prove two things: Alfa’s budget is dwarfed by AMG’s, and not a whole lot needed doing to our 2016 Car of the Year in the first place.

You’ll forgive me if we concentrate on the C63 and come back to the Alfa as a reference point because learning how to interact with this new age AMG is like trying to a cram-memorise a doctorate the night before graduation. There are eight driving modes, but at startup it always defaults to Comfort. Engine dormant, slipping away silently. Floor it (or tickle the steering wheel’s ear lobes into one of the fruitier settings) and the four pot joins in.

It’s not a £98,000 soundtrack. Let’s get that right out of the way. There’s much ‘augmentation’ going on – even what used to be the ‘sports exhaust’ button is now a sound wave icon. The engine’s lost the fizz and fury that’s so endearingly wild in the savage A45, but gained an almost supercharger-esque shriek from the electric turbo. Get into the throttle from low revs with the radio off and listen out for it. A wicked, hypersonic whine, like nothing you’ve heard in a German saloon before. Fascinating... if you never sampled the old V8. Like with so much of the C63, you’ve got to really buy into the concept.

But there’s a point at which speed becomes such a compelling argument in its own right that you have to acknowledge it. And the C63 is biblically fast, toying with the ‘I thought this was quick until the Merc disappeared’ Italian like it’s stuck in eighth.

But even this isn’t without complication. The C63’s diff housed motor allows it to do clever weight concealing things like torque vectoring, but to keep it hauling well into triple figures it uses a Taycan style two-speed transmission which is far from seamless. There’s a noticeable ‘step’ as the motor pauses and then re-engages. It’s more noticeable if you get into the throttle, then lift, then go again: say when you’re timing a track day overtake or choosing your moment on a sliproad. An on-off-on throttle hesitation confuses the powertrains. You must also remember to press the throttle through the ‘kickdown’ button at the end of its travel, or you don’t get full beans. Sometimes you have 671bhp. Sometimes you don’t. It feels unsynchronised.

So you’re never quite sure how big the hit of power is going to be when you tread on the C63’s throttle, which erodes your confidence in the car, when said hit is this big. You feel like the captain of a destroyer on the bridge, barking orders into the intercom for your officers to action. In the Alfa, you’re manning the engine room and the weapons bay all at once, getting stuck in.

The C63 counters with a fantastic gearbox: nine speeds still feels like too many (treat it as a seven-speed with two motorway overdrives and it’s easier to get along with) but the shifts themselves are instant and oh so crisp. The thicker metal paddles feel just as expensive as the Alfa’s slender blades, but the Merc’s move with the wheel.

Against all this, the Alfa is refreshingly simple. Naturally – it’s downright old, as is brutally exposed by its dated (though much easier to operate) interior. When it comes to the driving, you’re never wishing you could backtrack and have a crack at the same road you’ve just navigated with a few settings tweaked, because the Giulia lands on its feet in a sweet spot much more readily. Ignore A (All weather) and N (Neutral, weirdly) on the twist-lock mode switch, and go straight to Dynamic, where the V6 and gearbox down espressos and do as they’re told. In fact, this chassis is so friendly that within days of taking delivery, you’ll be twisting it all the way to Race mode, to unleash the raspiest V6 burbles and sharpest shifts.

Alfa’s longstanding weakness is the absent ‘individual’ mode – if you’re enjoying RACE, ESP is turned all the way off. That would be alarming were it not for the Giulia’s balance. The steering’s fast and attacks with a roll of the wrists, but the car moves as one and the chassis’ responses feels just as caffeinated. Prod the ‘bumpy road’ damper button to knock the suspension back to a superbly judged middle-stiffness and you’ve got a car that feels born to excel and on British back roads. Mindful of that corpulent kerbweight AMG’s lashed down the C63’s body control, but it can’t match the 500kg lighter Alfa’s compliance, and it feels leaden through compressions and ungainly over crests.

Why did the C63 go hybrid? It's not resulted in a greener car, or a more gratifying one

The brakes on this particular Giulia lacked feel, but I’ve driven others that were better. Like the steering, they’re set up to be instant: you don’t get much pedal travel and it’s easy to headbutt the dash with an initial squeeze. It takes a while to dial into, but once you’re settled, this is a gloriously agile entertainer than can also do the motorway schlep.

You’ll note only the Alfa is pictured doing anything remotely slidey. Sorry – the AMG just didn’t give me the confidence. Though it’s more progressive on the brakes, the sense of mass is inescapable and with the car driving all four wheels at such ruthless pace it’s had a complete character swap from the old fun at any speed C63.

This one wants to chew a road up, spit it out, move on. The day after we shot these pictures I accidentally discovered a fun cornering mode combo, but it’s still not as involving as it once was.

And it’s not as if it’s now a fuel sipper. We got 18.8mpg out of three days’ use – while the Alfa recorded 24mpg. So, why did the C63 go hybrid? It’s not resulted in a greener car, or a more gratifying one. Faster undoubtedly, but a confused proposition, with a compromised boot and a soiled reputation. Yes, AMG is quick to point to the bona fide F1 derived technology link, but is Merc’s recent F1 CV anything to shout about? And have you seen an F1 race lately? Overweight, over complicated cars that have to lift and coast or choose an engine map between dices. Remind you of anything?

I think AMG’s engineers have actually done an incredible mechanical job with a philosophically flawed concept here. And that’s what the new C63 boils down to: the wrong decision. Made when Mercedes F1 was irrepressible and automotive electrification seemed irresistible. It wasn’t a case of ‘either a C63 like this, or no C63’ – the V8 could’ve lived on. It’s been hybridised in the G-Wagen, the GT, the SL etc. But someone made the call that downsizing was survivable if it added fantastical pace. And just like Ferrari’s switch from nat-asp 458 to turbo’d 488, and Porsche’s ‘turbo flat four gate’ Cayman, something more soulful was lost along the windy road to Horsepowersville.