Yes, you can. You only need to be online when you first play the game. After the initial launch, you can play offline moving forward and are able to purchase from the ingame store. The XBOX Marketplace is not available obviously.
I just tried this and it works. I purchased a car offline and it worked fine.
DEFINITELY Freeze Timer and Score Multiplier. Specifically Drift point multiplier, cause I cannot complete the stupid drift challenges :P
we are looking at it. thanks for all the info
Well that's not fun
Its a REALLY good racing game =p