Well, we don't need a lot of new cars, I just love LFS (my S2 acc got banned from forum, so don't call me a hacker, search up for grkskate) and I think that new GT-R versions of actual street cars are all we need.
And as DeathInSelf said, slicks on street cars would be awesome, but I think that it's too much for a street car. So, semi-slicks would be a nice option.