My dude, the core game is just perfect, if you add more tracks, improved ui, soundFX, chill music and most importantly a GT4-like story progression I would buy on steam/itch.io without thinking twice.
(You probably know this) Although, I am not really sure cars manufacturers would be happy with the car models present in the tech demo, I would suggest going a GTA/beamng approach, I wouldn’t like to see a good idea like this one being ruined by big corporations.