The list of things I want to see:
1. Better AI - Why do you think single player exists. To have fun with the AI. But even after some patch updates in the last version of LFS, it's still not very good. What I want is better response when being bump drafted, they just jerk to the right/left, no braking when you get right in front of them, smooth overtaking, more chance of risky moves, and just, more 2-3 wide racing with no cowarding out. And last but not least when they draft they don't just stay in line, have them make a move for once and if they get blocked they go to the other side to try to pass. Average player online in LFS.
2. AI race on custom layouts created by the players - You know how when you load AI with a modded car and set them to race on a track and it does a bunch of coding before you can begin? Why not do the same when you spawn a custom layout using the X and Y configuration? In my thinking, when you spawn a custom layout, the game should scan your track and then have the coding implemented into the AI of the BEST path to follow. That would be very sweet!
3. Better aerodynamic simulation - This means...BLOWOVERS! in case you don't know, this is when the car gets spun around at a very high speed and goes backwards, the air gets under it and it goes airborne. This would be imo a cool addition to add to the game and the car doesn't have to have a wing in order for it to happen, it can happen sideways and even a front blowover. Plus, the grass, dirt and sand is not implemented properly, these things should be able to grab your car when you go upside down and you should be able to flip wildly!
And that is pretty much it so far for me.