January 13, 2009 While the firebreathing 5.2-litre V10 R8 supercar is clearly the performance king of Audi's Detroit NAIAS lineup, the Sportback concept unveiled does an excellent job of marrying performance, economy, stunning looks and practicality. Its 3-litre, 6-cylinder direct-injection turbo 'clean diesel' engine puts out 225 horsepower and 550 Nm, for a top speed over 150mph - and yet its average fuel economy nearly tips 40mpg. Ultra-low CO2 emissions are the result of smart decisions throughout the car, from the advanced exhaust emissions control, to electric systems like the power steering that consume no energy when they're not immediately in use, to automatic engine stop-start at the traffic lights and power-smart sunlight-white LED headlights. The Sportback's ultra-clean lines and fastback hatch somehow make this four-door coupe look sportier than some of its two-door contemporaries. Beautiful.