Porsche purists may have rolled their eyes when they heard it was going to launch its first diesel car – but stricter European laws governing vehicle pollution probably left the Stuttgart firm with little option.

The new Cayenne Diesel is a historic first diesel car for Porsche – but the German manufacturer has actually produced oil-burning vehicles before, if you go back far enough.

In the 1930s Porsche began manufacturing diesel-powered tractors and continued to make agricultural vehicles until the mid 1960s, when unleashed its iconic 911 for the first time.

Perhaps this explains why one of the activities at the UK launch of the Cayenne Diesel resembled a high-speed attempt to plough a field (a task, incidentally, which the car accomplished with consummate ease).

But then the hulking Cayenne has always been a capable performer both off-road and on – and has become Porsche’s chief bread-winner.

Last year the Cayenne racked up sales of 45,000 – that’s half of all Porsche’s worldwide registrations.

But the big 4×4 continues to polarise opinon because it lacks both green credentials and the svelte good looks of other Porsches.

The Germans have not ignored these criticisms; the Cayenne’s design, particularly at the front, was improved with a recent facelift and now it has been fitted with a powerful, yet relatively economical diesel engine.

Porsche could have taken the Subaru route and spent years designing its its own diesel power plant. Instead it acquired a controlling stake in the Volkswagen Audi Group, which gave it access to to some outstanding diesel units.

The Cayenne, therefore, comes with the same three-litre diesel power plant that can already be found in Audi’s Q7 and the Volkswagen Touareg.

I was expecting the Cayenne version to have been tweaked substantially to offer more power -Porsche is a sports brand after all. But this has not been the case, as the Germans wanted to keep development costs down and emissions below 250g/km for tax reasons.

The Diesel is still a more than capable performer, however. It will hit 60mph in around eight seconds and has a top speed of in excess of 130mph.

This is not as quick as some of the madder petrol variants of the Cayenne but nor is it as expensive to buy or run.

More impressive is the way the Cayenne goes about its business. It has a hugely torquey engine with excellent throttle response.

Overtaking is relatively painless and this Cayenne should also make a decent towing vehicle.

The car costs just under £40,000 to put on the road – substantially more than a VW Touareg with the same engine – but people will always pay extra for a more prestigious badge.

While there is only one trim level at the moment, you can choose from a large range of options which can easily add £10,000 or even £20,000 to the basic price.

One thing you will not need to stump up extra for, however, is an automatic gearbox. Porsche’s proven six-speed Tiptronic S transmission comes as standard.

In the current economic climate Porsche is remaining coy as to how many Cayenne Diesels it expects to sell.

But this more economical version of the car will surely go on to become the best-selling model in the Cayenne range - as well as providing serious competition for the Range Rover Sport, BMW X5 and various Mercedes models.

By Peter Carroll

FACT FILE

Model: Cayenne 3.0 Diesel

Price: From £39,404 on the road

Engine: 2,967cc, six cylinder V6, diesel

Power: 240bhp

Transmission: Porsche Tiptronic-S six speed, all wheel drive

Performance: 0-62mph in 8.3 seconds

Top speed: 133mph

Economy: 30.4mpg on combined cycle

CO2 emissions: 244g/km

Length: 4,798mm

Insurance group: 18

Warranty: Three years/60,000 miles