It looks pretty good, but what''s with the big mountain in the background? It just doesn''t fit the game. If you made it a cartoon mountain that might do the trick. Or change the ground to grass and make it look more like the background.
Then again, it''s your game, so do it however you want to! :]
I look forward to see more of this game, do you have any other screen shots?
It looks like it would play like those first person games on SNES (remember the first person vehicle scenes on the Star Wars games in SNES?). Not really using polygons, but scaling images in and out to mimmick depth. Unfortunately that just about eliminates the possibility of walls and such, but maybe that''s not the route you''re going...it just really looks that way.