Man I want one of these puppies, to bad when they come here (IF) they would be like 30k!
The secret is the little diesel's torque - 184lb-ft at just 1900rpm - plus a cleverly spaced set of ratios in the slick-shifting five speed transmission, great steering, and a nimble chassis. On the tight English backroads this combo means you can maintain a relatively high average speed by merely surfing the torque and not working the engine hard. The relatively tall gearing also means the A3 bowls effortlessly along the freeway at a relaxed 80mph, the engine turning just 2200rpm. I completed one 103 mile freeway stint at an average speed of 75mph - and still got 42.4mpg.
VW (and, by corporate extension, Audi) claim that their soon to be released common rail diesels will be 50 state compliant. The technology is advanced enough that the VW developers claimed the test mule they debuted to North America at the September 07 TDIfest in Montreal is lower in emissions than the then current hybrids from Honda and Toyota. Of that claim I remain skeptical, but there was zero observable exhaust visible during the few test drives allowed. I wasn't one.
VW's present 'delay' they claim is due to having a late change in the trigger sequence for the particulate trap burn-off. This change necessitated starting the whole approval process and 50k mile long term emission compliance test over again. Current estimated time for US release of the 50 state Jetta Sportwagon TDI is June, with full production ramp-up for September.