It would be a nightmare....
We would all become hermits!
But I'd want:
Every car with an interior view
More tracks, especially mountain road like tracks
a livery editor
a marketplace where you could buy or sell, car set-ups, custom liveries, or cars. In effect a financial marketplace where credits could be for use in the game.
private lounges
Public lounges
Race challenges
a developer feedback poll system: they ask, we feedback rather than we all winge
60fps
3d 1080P
external telemetry output (for cockpit devices etc)
Multiple garages.. could we have a garage at each track.. then you could leave cars there that were setup for that track.. which would mean you'd need to buy more cars....