The whole point of this award is to pick a car that is significant in the market, not necessarily significant to enthusiasts.
The choices this year were: Acura RL, Audi A6, BMW 6 Series, Buick LaCrosse, Cadillac STS, Chevrolet Corvette, Chrysler 300, Dodge Magnum, Ford Five Hundred, Ford Mustang, Honda Accord Hybrid, Honda Odyssey, Kia Amanti, Kia Spectra, Lotus Elise, Mazda 3, Mercedes-Benz SLK, Mercury Montego, Pontiac G6, Porsche 911, Saab 9-2x, Scion tC, Subaru Legacy and Volvo S40/V50.
Among those, which is likely to make a big splash in the general automotive market? Scratch all the luxury cars and sports cars because they're sold in too small numbers. The 9-2x and S40/V50 are reasonably priced but also not mass produced. Same with the tC. Cross the uberblandmobiles off the list too. That leaves us with the Chrysler 300, Dodge Magnum, Ford Mustang, Honda Accord Hybrid, Honda Odyssey, Mazda 3, Pontiac G6, and Subaru Legacy.
Of these cars, which presents something truly new to their segment? The G6 is made by GM and not as crappy as a Grand Am, but that's not really anything significant. The Odyssey and 3 are both really nice for their segments, but so were their predecessors. The Legacy has the new turbocharged GT model and a nicer interior, but is that a segment buster?
So that comes down to the 300, Magnum, Mustang, and Accord Hybrid. To me, any of these four would be a worthy choice.