Wonderful car, the Jaguar XF. So why you don't see more of them? Simple. In Britain, 80 per cent of all BMW 5-Series, Benz E-Class and Audi A6 sales are four-cylinder diesels. And 50 per cent are estates. With only a V6 diesel and a V8 petrol, the XF is aiming at just 20 per cent of the goalmouth. Having only a saloon, it's confined to 50 per cent of that 20 per cent. That's 10 per cent. Yes, Jaguar is turning its back on nine tenths of the market. D'oh!
This is the trouble with being a relatively small company. There's little spare money to invest in expensive new engines and body styles. But if you can't invest, you can't get the sales. So, er, you remain a small company. The circle is implacably vicious.
Luckily, Jaguar Land Rover's owner, Tata, is taking the long view, and at the moment is over-investing in search of long-term growth. JLR has spent big money developing the Freelander engine into something far more refined and powerful, good enough for a Range Rover - the Evoque - and a Jaguar. And it's an even more costly job than you'd think, since the Jag needs its own layout as it's mounted lengthways in the car.
So at last the XF's sales should be unshackled in Britain and the rest of Europe. This four-pot diesel will help. And yes, a rather slinky estate is coming too, though not for over a year.
Frustratingly even the diesel is still just a prototype; you can order it now, but deliveries don't start until September.
The engine isn't the only new thing; the transmission is an eight-speed ZF, as used by BMW. Land Rover and Jaguar are gradually adopting it on all their longitudinal vehicles. This Jag also has a stop/start system, with a clever starter motor that can kick it back to life instantly, even if you need to restart while the crank is still slowing down to a stop - a not-infrequent event that sends other stop/starts haywire.
On the road, the XF has mucho whoosh over a nice wide torque spread, and plenty of refinement nearly all the time. Sometimes you notice the 'box has been set for obsessive economy - get stuck behind a truck at a steady 50mph, and it goes for seventh, leaving the engine grumbling agriculturally at about 1,200rpm. But you always over-ride with the paddles. On a motorway, it's just a distant hum. And as the engine is a bag of cement lighter than the V6, it's even better in sharp corners.
As to the numbers, if you compare auto with auto (Jag gives no manual option), the BMW 520d is still a sliver more economical and speedy. But not so's you'd notice. If you like the XF, there's now no rational reason to buy a rival saloon.
We like: Still feels like a Jaguar
We don't like: Can't we have an estate now?
The verdict: For Jaguar, a car it needed years ago; for the rest of us, a pain-free economic policy
Performance: 0-62mph in 8.5secs, max 140mph, 52.3mpg
Tech: 2179cc, 4cyl, RWD, 190bhp, 332lb ft, 1760kg, 149g/km CO2
Tick this on the options list: Growler wheel nuts, price TBA
And avoid this: Intelligent High Beam, £200