Just finished Hypersonic and a couple of tracks on Time Attack and Hero Mode. Fantastic game.
Took a while to get used to controlling the vehicle in this mode but leaning properly allows for some crazy drift turns. I do prefer the lighter vehicles at these speeds.
I would've liked a map sometimes to check how far I'm away from someone in front or behind, and a rear view mirror button, though at high speeds neither of these would be really useful.
Give these people a bigger budget and a bigger team and I think they could create something amazing.