Flatout 2 would be a good addition, you can actually find it for pretty cheap for Xbox 360 as well. In general I'd have to say that I enjoyed the first one better, Flatout 2 while fun seemed to be more of a "racer" rather than a Destruction Derby-esque game.
I'd say Flatout presents itself more like a Rally game, just one where you get to race with opponents, the car damage is fairly realistic so avoiding collisions is often smart, or you will end up busting up your steering, and the tracks would not look out of place in a Rally game, they have this "cloused off circuit" look to them.
Flatout2 is much more an arcady destruction derby, cars can take much more damage before breaking down, and they don't really suffer any problems untill they reach zero health, it's a game that invites you to crash through as much stuff as you possibly can, and the tracks feel less cloused off somehow, it allmost feels like you are doing illegal street racing in FO2.
The two games are supricingly different in feel, with FO1 feeling more serious and trying to be more realistic, and FO2 feeling much more action oriented, much more "who needs realism, lets just break stuff with a smile!", and they are both very fun in different ways, FO1 requires a little tactics in your driving, trying to balance getting ahead without breaking your car, whereas FO2 is for when you just want to race around and destroy things.
Though i agree that some of the "stunt" events in both of them are a bit tedious, it's seems a bit tacked on, and some of them are just neigh impossible to get through.. they are the only bad part of the games really.