Audi showed a couple of new green energy power plants at the Frankfurt Auto Show - small and econ friendly cars where the major theme this year at the show.

Audi A4 E-concept Car

The The A4 e-concept features a 2.0 TDI engine returning a useful 58mpg and 129g/km CO2 via the usual Frankfurt 2007 fuel-saving measures: clean diesel engine, stop-start system, low-friction tyres and tweaked aerodynamics.

The e-concept also has detailed driver info: turn on the air-con or heated seats and it tells you how much extra fuel you’re using. For example Increase the cruise control by a few mph and it tells you how many minutes you’ll save for your journey, and how much diesel it’ll need. Maybe a bit too geeky , but it could make playing the mpg game an obsession - it could also be a safety risk if people pay to much attention to the gauges on the  dash board rather than road conditions around them.

Audi/Porsche Petrol Electric Drive Train

Audi also showed a full 4WD hybrid drive train, being co- developed with Porsche, involving a petrol engine, an electric motor powerful enough to drive the car alone and batteries in the boot. In an A6, with a 2.0-litre turbo, it would have the performance of a 3.0 petrol but use 30 per cent less fuel. The system will fit the A4, A5, the next A6 and A8 plus next year’s Q5 SUV.

One interesting historical snipit is that Porsche of course have a lot of experience with hybrid drive trains having developed a petrol electric drive for the Tiger tank back in the 40’s.