I think I could (maybe) like this. Looks kind of bland and simple (which I appreciate to be frank since Sega tended to go overboard with stuff like this in the past) but then again it also looks and feels way more approachable than Riders did IMO (Cartoony yes, but way too X-TREEEEEEEEEME to really be likeable) and doesn't seem to come across as being anywhere near mediocre as R did.
I think Sonic on foot while everyone else compensates with a vehicle (barring Eggman or Amy who have always had something of the sort in Sonic racing games) would bug me a lot more. While Sonic on foot feels more natural because we know the other characters can race him that way (Sonic R) or that there will be some kind of gimmick to compensate (Sonic Riders), I think that having Sonic on foot while everyone else is in a vehicle would probably feel a bit awkward in terms of the game design - how do you do items with no car? Specialty tricks, etc etc etc. Plus this puts Sonic a bit more on par with everyone else in terms of speed and makes it come across as being balanced. In this case, Sonic in a car (at least here) just makes better sense. Not to mention that this is a racing game, and as such handling the vehicle is supposed to be part of the challenge. If Sonic is just running, that either gives him an unfair advantage, or you have a running character that handles like a car, which would incredibly awkward and strange to control (see Sonic R).
Plus I'm hoping this game would be way less gimmicky than Riders in general. Racing games shouldn't have insane learning curves.
Anybody else kind of feel like this is a sort of spiritual sequel to Drift? Maybe its the design of his car (colored blue here). Nice to see them use a bit of continuity with the design of Amy's car and have a variety in the car designs via Eggman and Tails (it'd be pretty cool for Tails to have limited flight capability while no one else does or Eggman compensating for lack of speed by being a powerhouse with missiles). Here's hoping it won't have any of Drift's suck though. "Drift done right" would actually be nice.