You can change the difficulty by changing:
-difficulty level (rookie, normal, etc...)
-going promode (turns off restart and no flashbacks)
-drivers head lock (camera angle changes forbidden)
-anti-lock brake assist
-traction control
-something else...can't put my finger on it

It all pushes your reputation gained up a bit.

Cool thing too, you get sponsors that have stipulations.  You get about 6 minor sponsor spots and 1 major sponsor.  The major sponsor gives you double the cash.  So the stipulations range from "finish the race" to "finish 1st with no damage".

The damage realism is nice.  You can actually "die" or completely crash.  I hit the wall going 110+ mph and had clocked 134G's! haha

You can adjust the difficulty of the 24hr LM, but even still it's really tough bidness.  They time elapse it obviously, but it's about a 10min race *shrug*.

Oh oh, and you can sell your cars through "ebay motors".  They have a demo derby style thing, pro togue races, muscle car, and whatnot.  If you need quick cash, you can race for another team.

I actually transferred the $5 I'd used to reserve MGS and got this instead.  I needed something I can walk away from easily.