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BMW's most successful 5 Series? The 520d - by a considerable margin. Four-cylinder turbodiesels also dominate sales of the Mercedes-Benz E-Class and Audi A6. Which explains the arrival of Jaguar's new XF 2.2 Diesel. It's been a long time coming, but it'll soon be Jaguar's most important and biggest selling XF.

Key Facts

Pricing: £29,000 (estimated)
Engine: 2.2-litre, turbocharged four-cylinder diesel
Transmission: eight-speed automatic, rear-wheel drive
Body style: four-door saloon
Rivals: BMW 5 Series, Mercedes-Benz E-Class, Audi A6
CO₂ emissions: 149g/km
Combined economy: 52.3mpg
Top speed: 140mph
0-62mph: 8.5 seconds
Power: 188bhp at 3,500rpm
Torque: 332lb.ft at 2,000rpm

In the Metal: To be confirmed!

It's swirly, with this car's 2012 model year styling hiding under some stick-on camouflage. We've seen it without that, but until it's officially revealed at the New York Auto Show later this month we'd have to kill you if we told you. Be patient: it's worth it.

Inside much the same is true; there are changes, but we're sworn to secrecy for now. All we'll say is, if you like the existing car, you'll not be disappointed.

Driving it:

We might not be able to tell you in detail how the new XF looks, but we can tell you how it drives. More than merely a drop-in of Land Rover's in-line four-cylinder turbodiesel, the 2.2-litre unit has been extensively revised for fitment in the XF - not least as it sits north-south in the engine bay as opposed to east-west in other installations.

Being a Jaguar there's a huge amount of emphasis on refinement. It has been successful too with things like a double-skinned sump, acoustic deadening and a host of other obsessive NVH (noise, vibration and harshness) details resulting in near silent operation of the 2.2-litre unit on the move. The quiet diesel is mated to a new eight-speed automatic transmission, which shifts through its numerous ratios almost imperceptibly. All those gears have allowed Jaguar to offer quick take off and super-low rev cruising, with 70mph seeing the rev counter's needle sitting at just over 1,500rpm.

The engine's low-down urgency means it feels every bit as quick as its 8.5-second 0-62mph time suggests, its flexibility and easy performance not making it feel like the poor relation to the XF's six-cylinder powerplants. Fitted with stop-start, the engine is quick to re-start when pulling away too, Jaguar claiming it fires up faster than any of its direct rivals, better coping with those indecisive moments where the engine's about to shut down and the driver asks for power.

Always a tidy handler, the 2.2-litre turbodiesel's lesser bulk does make the XF's nose feel a bit more eager to turn in, and the steering's weight and feel are also impressive.

What you get for your Money:

Jaguar has yet to firm up pricing and specification, but it's promising a highly competitive price point and comprehensive equipment levels. We'll know more later this month, and when it finally reaches showrooms in September.

Worth Noting

The 2.2-litre unit produces 188bhp, giving it the highest output among its German rivals. They're mostly 2.0-litres in capacity, and all offer better CO₂ emissions than the Jaguar - BMW's 184bhp 520d auto achieving 137g/km. The British car's 52.3mpg official combined consumption figure is competitive. If outright tax efficiency is your goal then the XF 2.2d is bettered, but if you can stomach a tax band higher - the lower purchase price helping offset that - then the XF is still competitive.

Summary

You can't fault Jaguar for chasing volume by adding a four-cylinder turbodiesel to its XF range. When the result is as polished as this car it's a shame buyers have to wait so long until it reaches the showrooms. All they need now is an estate. Word is that'll be along next year...