While this E-Class...

While this E-Class, seen at last week"s Detroit Motor Show, may look like a regular saloon, under the bonnet is BLUETEC - Mercedes" latest clean diesel engine technology. On sale later this year in the 3.0-litre V6 E320 CDI, the system features not only a particulate filter capable of reducing harmful emissions by up to 98 per cent, but also a clever catalytic converter.

Using technology called DeNox, this not only cuts carbon monoxide and hydrocarbons, but also nitrogen oxide emissions - so much so, the BLUETEC engine will comply with even the most stringent of US exhaust gas limits.

In the future, the system will also feature AdBlue - a special chemical which, when added to exhaust gases, reduces nitrogen oxides by a massive 80 per cent. Requiring minimal maintenance, this chemical is kept in a separate tank, and topped up each time the vehicle is serviced.

AdBlue is still under development, but it"s already being used by Mercedes" trucks, and is likely to be seen on passenger cars before long.