Despite America's on-again, off-again love affair with passenger diesels, Mercedes-Benz sticks to its guns with a new concept executive-class sedan unveiled at the New York International Auto Show.

Powered by a 2.2L, four-cylinder turbodiesel, the E250 BlueTEC Concept promises 28 mpg city/39 mpg highway--those are conservative estimates--and would regularly hit well over 40 mpg, says the company. The secret to this efficiency is found in the car's 7-speed automatic transmission and its next-generation emission

Audi's first domestic clean diesel, the 2009 Q7 TDI sport-utility vehicle, will be eligible for a $1,150 tax credit, the manufacturer has announced. The vehicle, which will begin shipping this month to dealerships, starts at $50,900, priced smack dab in between the 3.6L V-6 and 4.2L V-8 gas engines already offered on the Q7.

The Audi Q7 TDI is up to 30% more fuel-efficient than a comparable gas model (also cutting greenhouse-gas emissions), the manufacturer claims. On highway, it will carry an

The current Audi A8 has been on sale since 2003 and since that time has only received a minor facelift to keep it fresh alongside the updated Mercedes Benz S-Class, Lexus LS and new BMW 7-series. The minor styling changes implemented during the recent facelift will have to soldier on for at least another year as the next-generation 'D4' A8, according to Audi CEO Rupert Stadler, won't arrive until the second half of next year as a 2011 model Speaking at the carmaker's annual meeting, Stadler said the new A8