Ok thoughts on the comments:
I think Unity is a sure front-runner for the game engine.... it can be ported to other platforms and there are a lot of templates out there. Cannonball is certainly an option, but it's literally reverse-engineered source code from the arcade roms, so you are pretty much limited to an outrun clone and I'm not even sure how legal that would be.
I've always dreamed of making a Cannonball game (the movie). I think it might be a massive undertaking though considering half of the film was about setting traps for the other racers, wacky situations, ect..... It'd be the first racing game with a story mode. I also had that idea about a 2d racer with landscape paintings for textures, but that would be all on me (or anyone else that can paint) and the results might not be what everyone is looking for.
I think a working prototype, regardless of the direction we choose, needs to be the first step. If we can't make a car model race through a stage with some traffic and have it feel right, we are just kidding ourselves.
There are a ton of great places throughout the states (hell, throughout WV alone) that would make great courses or course elements. Ideally it'd be nice to represent every state, but fifty courses would be insane.
I'm all about the arcade style racing myself.... each car would have three stats.... top speed, acceleration, and handling, those wouldn't be based on the real cars' stats at all and you can't change or upgrade them. That's just me though.
In regards to the cars I suggested, I only suggested them because they look interesting visually. If you are going arcade racer then real world specs don't matter which is why some of those cars are really slow compared to the others.
Something else that warrants discussion is traffic. Are we going to have some or will it just be other ai cars? If we do is it going to be intelligent traffic, or traffic on rails like outrun 2k6? There are actually merits for both. Some people actually prefer the "stupid" traffic of 2k6 because cars will always be in the same place every race, so the game becomes more of a puzzle in regards to avoiding cars and using their slipstreams to get through the course as fast as possible.
As far as money, ect goes let's not put the cart before the horse. I didn't want to bring it up, but I have a heart cath scheduled for Monday, so if something goes wrong or a get a poor diagnosis from what they find, I might not even be able to help and thus far I'm the only programmer to have volunteered.