Just completed FlatOut: Ultimate Carnage (the XBox 360 era HD remake of FlatOut 2) (all race series gold, including grand finals, at least some medal in everything else, didn't get all golds and cheevs but I don't think I'm physically capable)
FlatOut was very good, in a slightly low production quality way and BurnOut Paradise is pretty special, although it can feel like a grind and the constant slow mo's can get a little old so I think FlatOut: UC is the best knock about racer I've ever played, its just amazing! There nits I could pick like the difficulty curve is a little odd - I breezed the grand finals once I worked out to buy Frank Malcov's car for the derbies while the hardest race series was the one where you only had 1 lap to go from 12th to 1st
Also getting a bronze on the time trials was a real challenge for me and anything more seems like witchcraft!
(although maybe you have to use the cars you unlock by getting gold in Carnage mode, but that's witchcraft too!)
But yeah, awesome mix of crashing, vehicular murder and racing, much better than the Carmaggedon series ever did because the racing matters and the physics engine isn't from the moon!
Besides what other racer series lets you do bonus stunt modes where you fire your driver out of the window and guide him through rings of fire, play darts with him as the dart etc.
If you want the achievements and world leaderboards play it now before they switch (the purely optional to use) GFWL off! (although you probably don't knowing you lot!)
Shame someone else other than Bugbear did number 3 and apparently made a cock up of it, BugBear are, apparently working on something new to race with though! 'Cited! FULL LIST