I want to add to your list (in bold)
- Car Affinity - no need to level up each individual car
- Prize Car Selection
- New physics (took me a while to get used to the steering)
- Damage simulation is better
- Graphics (think GT5 but all premium cars)
- Sound is exponentially better
- 16 person multi-player
- Realistic speed differences in between classes. Before I could catch a R2-based C6.R with the far less powerful R3 M3.
- Realistic high-speed reactions from driver & car.
- Menu layout (not as straight forward to FM3)
- Nearly the same cars as FM3 (with all DLC) but a few new additions. Yes it's hard to add every car in the world (GT5) and there have been very few new additions as of late, but I guess I expected more. Oh and no one wants to race/own every single Sub Compact car in the world...when was the last time you even saw one at the track? At least give me my 335i.
- Cannot see stats/price of Prize cars when you get to select.
- Tire wear/fuel consumption still too slow for endurance racing. Should consume faster for realistic pit stops.
- Not enough North American tracks! VIR, Barber, Lime Rock, MoSport, Mid-Ohio, etc..