"This signals that clean diesel has arrived," said Ron Cogan, editor of Green Car Journal, the trade magazine that awards the prize.
Volkswagen's US chief, Stefan Jacoby, said diesels have emerged as an alternative to hybrids such as Toyota Motor Corp's popular Prius.
"It's a breakthrough in this country," Jacoby said. "it's a real alternative to hybrids. It brings fuel consumption down, it's environmentally friendly, and -- this is a difference with a Prius -- this is really fun to drive."
They simply require less maintenance, cost less us less raw materials to manufacture than nearly all other "eco" technology...
Volkswagen's five-passenger Jetta TDI, which boasts a fuel efficiency of 41 miles per gallon at $21,990.
The Jetta TDI beat out finalists including BMW's 335d diesel sport sedan, Ford Motor Co's Fusion Hybrid passenger sedan, General Motors Corp's crossover Saturn Vue 2 Mode Hybrid, and the smart fortwo mini car.
"This is the vehicle that stood out among all of the five finalists as the one that really exhibited the greatest environmental achievement," Cogan said. "You get 30 percent better fuel efficiency, on average, with a diesel, and a commensurate reduction in greenhouse gases."