It's got a couple of strikes against it.

1) It's a diesel and diesels have [link|http://www.findarticles.com/p/articles/mi_m0CYH/is_17_6/ai_90792852|trouble meeting the coming US emissions standards]. Also, US cars have to meet emissions standards for [link|http://www.law.cornell.edu/uscode/html/uscode42/usc_sec_42_00007521----000-.html|10 years/100,000 miles], so it will probably require more than a particulate filter to meet the standards.

2) It's extrememly light weight. 450 kg = 992 pounds. How can such a lightweight car meet US auto safety regulations (crumple zones, air bags, etc.)? I'm not sure that a 4 passenger auto that weighs < 1000 pounds can, though it apparently will come with air bags - when it's available in "2009".

I also wonder whether that 157 mpg number is obtainable in the real world at present. Note what a more typical [link|http://www.ecobusinesslinks.com/fuel_efficient_vehicles.htm|168 mpg] vehicle looks like (scroll down)...

It's great that people are continuing to push the envelope like this, but there is no secret to high mileage. What we need are new materials (lighter, stronger structures); lower friction engines, bearings and drive trains, lower rolling-resistance tires that still are safe in the rain, and better emissions and safety systems that will allow real world high-mileage vehicles to meet existing rules. (Or we need to have special safety requirements for high-mileage vehicles - maybe like special, low speed limit lanes for them.) And it needs to be reliable and cheap!

Cheers,
Scott.