Best game I've played in a really long time. Smooth, playable, re-playable, and excellent graphics without crazy bells and whistles. AI could be harder, maybe more tracks. DON'T add upgrades, its simplicity is what makes it so enjoyable.
AI could use a little work. On LVL 10, the CPU doesn't buy anything, and has $5500. It makes it beatable, but not much fun, as it gets easier as the level progresses. Otherwise, loved it 5/5
I've been playing for a while and sticking with it. I think planning better will just come with practice. I've already beaten sandbox and normal without losing a life. Took a fair number of trys though