Outrun races, and NFSU2 Tuning model.
I think outruns from NFSU2 would help the end game tremendously, whether or not you get rep / bank gains from them is another discussion. But this game is awesome, I haven't really raced against other players much online due to them having a much higher level than me. But the way outruns work, you can beat someone who has an insane car, using a much less powerful car yourself. It's more skill based and it's perfect for the Free-Roam facet of this game. Pull up to someone driving around, honk your horn at them, they honk back and it starts a countdown 3, 2 ,1 race starts. For those of you who aren't familiar with outruns from NFSU2, you have to take the lead by passing the other player 1vs1, and then get 1000m lead to win. This would make the game much more competitive from a PR standpoint with vehicles. A 250 PR 180sx could easily take down a 400 PR 180sx just off of better driving and deception. The perfect mode for free roam day or night. I would really love to see them in this game and don't think it would be hard to emulate or copy.
On another note, I love the customization we currently have with the varying amount of mods, motors, cars etc. If we could take it another level deeper though by being able to tune gear ratios, suspension stiffness, powerband, like we could in Need For Speed Underground 2, the possibilities are endless and it could be what the difference is between 2 identical cars, another facet of the game that you could spend hours and hours perfecting your build and tune for each vehicle... This might be the best Need for speed ever if these 2 things were implemented in my opinion, and give the game a much longer life expectancy. The end game would never get stale. I hope to get a response from a dev or someone within the EA team in regards to whether or not this is a possibility or something that would be considered.