Cayenne will be first diesel Porsche

February 2009 is a watershed month for Porsche; it's either the month it sells out completely and ruins everything the brand stands for, or it's the month it finally drags itself into the realities of 21st century motoring.

Either way it's a landmark - Porsche will finally get diesel power. It was difficult enough for some purists to take a Porsche SUV, so the Cayenne Diesel will prove a further blow. But there's no doubt that it makes sense in our eco-aware age.

Porsche claims the derv Cayenne comes "in response to changed legal regulations, resulting in tax incentives for vehicles with diesel engines." Or in other words, Porsche wants to sell more cars. So, an Audi-sourced 3.0-litre V6 diesel engine is slotted under the Cayenne's gargantuan bonnet, resulting in a 240bhp 4x4 generating 504lb.ft of torque, yet returning a claimed 30.4mpg on the combined cycle and 244g/km of CO₂. It's not the cleanest car on the road, but compared to the 358g/km of the Cayenne Turbo it's a member of Greenpeace.

The Cayenne Diesel will only be available in Europe to begin with, and Porsche is confident it will bolster sales of a car already doing surprisingly well, given the current financial and environmental background. Over 45,000 Cayennes were sold over the last financial year, without a diesel option. And the Cayenne's green drive doesn't stop at the black pump either - there's a Cayenne Hybrid on the way before 2010, as well as a new range of cleaner direct injection petrol units before that.

The Cayenne Diesel will cost just over £40,000 when it goes on sale early next year, with a Tiptronic-S auto gearbox and a cleaner conscience as standard.

Mark Nichol