The cars do feel a little floaty, particularly in three specific ways (pardon the technical mumbo I might spew but the devs will probably recognise the third one)
1) Hitting movable objects, they affect the car too much. Chris knows about this - those barrels
But the pillars in the tunnels are a big culprit too. They affect the car's angular travel too much (I don't mind them shunting me left/right or slowing me down but the buggers always spin me around or flip me over) and that does make them seem like the small physics objects have more weight to them than they should.
I know that's a WIP though.
2) The car bounces on practically every landing on a jump, and it feels like it comes off of the ground too easily as well. I don't particularly feel that the environment's gravity is too low (the cars are a bit bigger than Rollcage's, IMO, so it physically feels about right - maybe could be a little heavier, but that's nitpicking), but the car doesn't really 'stick' to bumpy terrain like it did in the classics. Whether this is a limitation with how the physics handle suspension travel/body collision or whatever, I don't know - that's dev stuff - but the bouncing is annoying and it also does ruin the flow a little. It feels like the wheels need some downforce as well to try and help the car stay on bumpy ground?
The potentially-technical one.
3) People have cottoned on to the car inexplicably taking 'ages' to fall off a ceiling. I've noticed it too, the car's downforce is acting on nearby surfaces even when it's nowhere near and in tunnels I've actually had the car 'float' for a few seconds before the game decided it was going to let the car fall to the road. I don't know how that could be changed, or if it should, but it's a strange thing I've noticed that can throw people into thinking the car has lunar gravity when it doesn't