Only vehicles that are new or significantly changed each year are eligible. I'm sure they like the new 3.5L engine and the available Hybrid. And it's not like there was a lot of competition this year:
"Among competitors for Car of the Year were the Chrysler Sebring, Saturn Aura, Nissan Altima, Kia Rondo, Honda Fit, Mercedes-Benz S Class, Volvo C70 T5 and the Volkswagen Rabbit."