http://www.duemotori.com/news/eco_ca..._emissions.php

sample quote:

Low-friction gearbox The TDI's power is transmitted onto a newly developed six-speed manual gearbox that is characterised by greatly reduced internal friction. It has been specially tailored for the high-torque of the TDI engine – its transmission ratios are slightly longer in third to sixth gears. Like all Audi gearboxes, its gear changes are playfully light and extremely precise. The gear change indicator in the driver information system encourages an economical driving style. It indicates which gear is selected and if another gear is judged to be better while driving steadily, it will show this as a recommendation.....
The power steering has also been thoroughly modified – its effectiveness has been improved by around 50 percent because it is now fed hydraulic energy by a demand-controlled vane-cell pump. In contrast to conventional power steering pumps, which constantly recirculate large volumes, it only pumps as much oil as actually needed at that very moment..... On the automatic air conditioning system, Audi uses an innovative, thermostatically controlled refrigerant circuit with an internal heat exchanger. Along with intensive precision work on other components, has greatly improved the efficiency of the system – the new automatic air conditioning system requires 20 percent less fuel that its predecessor model did.....The A4 2.0 TDI e Concept glides smoothly and effortlessly through the wind. Its body is fundamentally extremely aerodynamic. Its boot lid has been given a slight additional separation edge. Specially designed alloy wheels improve the airflow across the wheels and wheel arches, while a sporty tuning has lowered the body by 20 millimetres. This modification reduces the frontal area, improving air resistance.

 

Problem with Audi is that resale value is ridiculous so you probably won't be able to afford one and that new ones are overpriced