Road Test: Porsche Cayenne Diesel 5dr Tiptronic S

This is a monumental moment for Porsche. It built its first SUV six years ago and broke a few rules doing that. Now it has put a diesel engine in the Cayenne - the first diesel in the company's history.

It's exactly the same 3.0-litre TDI that appears in the VW Touareg - which makes complete sense as the two cars were co-developed - so ithas 240bhp and 405lb ft, with a combined fuel figure of 30.4mpg and 244g/km of CO2.

There aren't any tax benefits over the V6 petrol Cayenne, but there are environmental ones, so at long last you can drive a Cayenne without the guilt of the world on your shoulders. Which is why it would be good to have an enormous badge shouting ‘DIESEL' on the boot. Sure, it's huge, but there's no more reason to hate a Cayenne diesel than a BMW X5.

And for those worried you can't drive it like you would a Porsche, you needn't be. There were concerns that because Porsche opted for VW's V6 engine, not the V10, it would feel a bit flat and underpowered.

It doesn't. Besides, Porsche thinks there's little point in the V10 because that gives similar mpg and CO2 figures to the petrols already available in the Cayenne. The new engine mapping on this Cayenne helps the V6 feel sharper than in the Touareg, and there seems to be less turbo lag. OK, so the diesel Cayenne doesn't feel like it will keep on pulling forever like the V8s, and runs out of puff above 4,000rpm, but it's not slow, with an 8.3secs 0-62mph time. 

On the motorway, leave the transmission and suspension in normal. Porsche has tuned the gearbox so kickdown is perfectly quick and there's a torque lock-up so it's not constantly changing down.

Get to any corners, though, and you'll want something more. In normal mode, if you get to the apex and nail it there's too much delay before engine and gearbox react to get you on your way again. This might seem like weird criticism in an SUV, but the Cayenne drives so incredibly well that any slack in the drivetrain is too obvious.

Better to drop it into Sport, which is the first time VW's 3.0-litre diesel has had that button. That way, it tightens the throttle response and also means that the gearbox is in the right cog for when you want power. Unlike other sport modes, it also avoids holding onto gears too much, so you can drive sedately with it engaged.

All of which means you now have three choices from VW when it comes to an SUV. Touareg, Audi Q7 or Cayenne. The Porsche is the best compromise - it's better on-road, better off-road, but not better politically. Bring on the big badging.