In the PS+ Edition you don't have access to all cars, races and tracks. I've raced a bit, then I unlock a car, but when viewing that car there is a shopping basket next to it, saying something like to be able to access this content I will have to upgrade my PS+ version to the full retail version.
The free games are, and are playable while you still have an active PS+ sub. But Driveclub PS+ edition has been promised for way over a year now. Wasn't one of your normal "free" PS+ games, more like a playable demo with full trophy support.