I downloaded Need For Speed ProStreet from the EA website and have been playing it for a couple of weeks on the PC and really like the game.
It is different than the previous games in that you are now racing to be the King of the Hill in Drag racing, Speed, Grip and Drift and then the overall King of the Hill (the villian in the game drives an Evo X). As each discipline is different you have different cars for each and can have a backup car just in case you total a specific car and don't want to lose the progress you have made on a particular race day. Racing is done at "Race Days"on dedicated tracks with multiple types of racing being done on each race day (think rolling up to the track with your trailer full of your race cars) as oppossed to the previous games where you raced on the street. Damage is cumulative and you can fix it with either $$$$ or with markers you win as you go through the game. You can also total your car and as such you are better off saving your markers early on and paying for the dents and dings with cash as later in the game you will tear some sh*t up and it will be real costly to use cash! You can still buy upgrades for your cars (driveline, suspension, engine, turbo's, NOS etc) and can tweek the settings to include your aerodynamics but the biggest difference is that your body, paint and wheel options are free. The more you win the more that is available to add or modify.
I have a 1000WHP Supra for Drag racing, A Porsche Cayman for Speed, A Silvia S15 for Drift and an Evo IX for Grip.
The online game play is like being in the game as people will start either specific types of race servers or will start race days. Regardless whether you are in the game solo or on someone elses server, how you finish is fed to the EA website for overall standing in the ProStreet community. As such you are competing for King of the Hill in each discipline as well as overall worldwide. Personally I am having a ball with the Supra on Drag servers. 1K WHP and 3 stage NOS has seen me run 6.98. There are even wheelstand only servers to see who can do the best wheelstand.
The Evo X is available as are all of the Nissan GT-R's to include the new one. The available cars is pretty impressive from an AE86 and old Hemi Charger (really fun to drift), early American muscle cars and Japanese sports cars up to Aston Martins, Ferrari's, Lambo's as well as the new Camaro and Challanger.
I have not played this on the Xbox as I downloaded it before I bought the 360 but if you are into racing games I highly recommend getting Need For Speed ProStreet on the PC.