RACER is the best game there is! there is nothing more realistic (havnt played GPL yet tho). but its not made by dophinity, its made by a single person, Ruud Van Gaal. the racesimcentral forums is where you can download lots of cars and tracks and see some of the things people are currently making. Ive tried making cars for this game, this is what i have so far:
Racer Home
RaceSimCentral Forums - Racer
Racer Xtreme - cars and tracks