If the Audi A3 TDI won the Green Car of the Year award, who did they beat in the competition? Details inside.

Green Car Journal has named the Audi A3 TDI the 2010 Green Car of the Year.  The magazine and web site gave the A3 TDI the award over the Honda Insight, Mercury Milan Hybrid, Toyota Prius, and Volkswagen Golf TDI.

"This compact luxury car features an impressive EPA estimated 42 mpg on the highway - a 50 percent highway fuel efficiency improvement over the standard gasoline engine A3," says Green Car Journal head Ron Cogan.  "Plus, this Audi's quiet, clean diesel engine delivers loads of low-end torque and a fun-to-drive experience, all with the functionality of a 5-passenger hatchback."

The award is decided by a six-member jury, which includes International Council on Clean Transportation president Dr. Alan Lloyd, Global Green USA president Matt Peterson, and Sierra Club excutive director Carl Pope.  Also on the panel is automotive enthusiast and talk show host Jay Leno, car designer Carroll Shelby, and Jean-Michel Cousteau, the founder of the Ocean Futures Society and son of oceanic explorer Jacques Cousteau.

Its an honor that also pleases top brass at Audi.  "In winning the 2010 Green Car of the Year Award, the Audi A3 TDI demonstrates the bright future that clean diesel technology provides through reduced fuel consumption and greenhouse gas emissions," said Audi of America president Johan de Nysschen in a press release.

The Audi A3 TDI uses a 2.0-liter engine, mated to the S-tronic dual-clutch automatic transmission.  US retail price is $29,950.

Gallery: Audi A3 TDI is Green Car of the Year 2010