What is it?

The Porsche Panamera Diesel: the ultimate hate-symbol for the ‘air-cooled’ mob, or a Panamera with reduced running costs, depending on your outlook.

Technical Highlights.

An Audi diesel engine with 251bhp and 405lb ft, as already seen in the A6, A8 etc. Kerb weight is now 1880kg, 120kg more than the V6 petrol. The catalyst and particulate filter are mounted very close together to improve exhaust sound.

For those of you wondering why Porsche is sticking with this engine just as Audi launches a biturbo version for the new A6, apparently the new motor won’t fit under the Panamera's low bonnet line.

The Diesel is 2WD only, and it has an 80 litre fuel tank. Curiously, a 100 litre tank will be an option from the end of the year, but supplier issues mean it won’t be available from launch.

What’s it like to drive?

Very accomplished. It’s uncannily quiet and smooth, and it pulls much harder than the figures suggest. It probably sounds better than the wheezy V6 petrol too. Economy is impressive with a claimed 44.8mpg combined. This car doesn’t use the PDK transmission, instead it has a conventional 8-speed auto, and it’s actually much smoother than the dual-clutch ‘box. The combination of big shove and torque-converter is very effective.

But, and you know there is a but with this car – for all it’s cleverness, it’s hard to square the overt ultimate-Autobahn-slayer-styling with something that will only just nip under 7 seconds to 62mph. The Panamera diesel is fast enough for what it sets out to do, but not fast enough to wear the clothes it does.

The handling isn’t noticeably blunted, and the steering is especially good. All the test cars were on the optional air-suspension, and we know it can be caught-out on very sharp impacts on UK roads.

How does it compare?

At £62,134, put bluntly, it doesn’t. A BMW 535d nails it for performance and economy. However, the Panamera’s cabin is of Bentley quality, and it is a sensational European touring machine. The trouble is, you get the feeling that this is car Porsche felt it had to make, rather than actively wanted to make. Porsche's official line is that 'diesel should not be a performance derivative, and we will never develop our own engines, preferring to buy them from Audi instead.'

Anything else I should know?

If you can afford it, this is a very fine way to travel. But only if you can handle being nailed in a straight-line by other diesels - the new Audi A6 TDI Biturbo among them - and value what remains a very special cabin.