What is it?
This is the Audi Q7 3.0 TDI Clean Diesel. Over the next few years, diesel cars are going to get slightly more complicated. Strict Euro6 emission regulations kicking in from 2014 will require most oil burners to use a urea-based additive called AdBlue, which, with engine management changes, almost eliminates smog-generating nitrogen oxide (NOx).
The need to meet similar regulations in the US right now means selling the technology in Europe, so the newly facelifted Audi Q7 3.0 TDI Clean Diesel is the first low-NOx diesel to be offered in the UK, and the first to need AdBlue. Its additional 23-litre tank, good for over 18,000 miles, is replenished during services, its filler positioned beside the diesel’s. A special tool is used to remove its cap and prevent mis-fuelling.
Revised injection and emission controls complete the Clean Diesel modifications, which add a sizeable £1500 to the price of the still-available conventional 3.0 TDI V6. NOx output drops by around 90 per cent, but the fuel consumption and CO2 gains are minimal, limiting the point of this version unless you want to drive greenly, in which case the hefty Q7 makes an odd choice.