I think some of those with better systems are getting too defensive about the performance concerns.
No one in their right mind is going to ask that grid slots be reduced or that no new graphics features be introduced. However, it's still important to give the options for those who need it to alleviate load on their system. The current lowest detail LOD turns cars into blocky lego structures. If someone has to deal with that to get a playable 24 fps then so be it. However, I think they should have the option of dialing down their graphics that far if need be. It's not going to stop anyone else from using hi-res textures and 16xAA/AF.
Speaking as someone who has had to tweak a mid-range computer, I think the LOD reduction system is sometimes optimistic about what can be smoothly rendered. Perhaps some form of manual customization is due for the automatic LOD reduction? For example, setting a maximum car LOD level at all times. Or maybe a user defined max number of car polygons rendered, where if (# of cars rendered * #of polys per car) exceeds a certain number, all cars are dropped to a lower LOD. Or even a simple minimum FPS setting that the LOD reduction system tries to maintain.