Definitely a 5 for uniqueness this Jam. It is a shame the controls are a bit floaty - but I think that's understandable for a 48 hour Jam. But there is plenty of other cool ideas that I can imagine could be a good foundation for an interesting racer.
For example, there have been games were collecting the same power up multiple times in a row upgrades it (Diddy Kong) but your element of randomness adds a Risk/Reward. I'd think it would be even better if there were just "Upgrade Pads" around the map to allow rolling your current held item more often to bring this element to the forefront more.
The purchase of sections of the Map is a unique addition I haven't seen before either. It give me a good reason to get coins. My only suggestion would be to have the Purchase Area separated from the Benefit Area so that I can use it immediately after I buy it rather than having to wait a lap. Also, instead of having things pop up and down, maybe just let the owner use the bonus by themselves. For example, you could just have secret paths with barriers that are only passable to the owner or have boosters on the ground that only activate to your player. That might be easier.
This game has really got me thinking. So Kudos and good luck with getting on the GMTK Winners Reel.