So what advance drivetrain system was employed this time? Actually none; just some green-thinking applied to conventional mechanics. The transmission of the classic 1.9L diesel four-banger will simply be fitted with taller gear rations (widely-spaced gears may reduce fuel consumption by lowering engine speeds in varying power bands). With decent results in combined city/highway mileage, the technique is fairly effective, but frequently overlooked. Throw in a set of grabby, low-resistance tires, and the new A3 is greener than ever at no additional input cost.
Here in US the A3 has only been around for about a year. It's powered by a slightly larger 2.0-litre petrol in-line four, rated by EPA at 23/32 mpg. Not too impressive. But considering its 200 hp output, Audi A3 might just be one of the greenest and most dynamic sports wagons available.
Source: Whatcar
Source: http://www.goodcleantech.com/2007/08/audi_a3_gets_even_greener.php
