Lots of drama with driving game studios.
Psygnosis, makers of Wipeout, everybody moved to other projects after bought by Sony - defunct 2012.
Eden Games (V-rally), everyone good left the company after bought by Infogrames (Atari).
Reflections (Destruction Derby, Driver, Stuntman), now make Watchdogs & The Division.
Namco lost everything that was good about Ridge Racer after PS1 era.
Polyphony was revered for Gran Turismo in PS1 & PS2 days, and like the success of PlayStation went to Kutaragi's head, so did the success of GT go to Yamauchi's head. The studio takes forever to produce new titles and they're not that great.
Criterion, a studio with some of the best rated racers in PS3/X360 generation no longer exists as a real studio (after the studio heads went literally mad).
Codemasters (Colin McRae Rally, Dirt Rally) still going pretty well.
Forza is probably the most successful long term series. (Metropolis Street Racer, Project Gotham Racing, Forza, Forza Horizon).
