I am sure that someone has suggested this before, but maybe if it gets suggested enough, they will do it.
My suggestion is the ability to control where in the lane the car drives. In general, the car stays to the middle of the lane. But, maybe on a major highway, if you are in the left lane, you want it to go more towards the left side of the lane. Or maybe you are coming up on a large truck hugging the line and you just want to adjust over to give them more space. I have heard this suggested in reference to Motorcycles in California, where they are allowed to ride down the middle of the lane, so being able to bias to one side or the other allows for more room. For me, I am on one lane each way roads a lot, with large shoulders, I would prefer the car ride more towards the outside line.
As for control of it, allow the user to choose in a setting for the right steering wheel control, have the left/right motion be either to adjust the lane position or change the following distance. I know I would probably adjust the lane position more than I would adjust the following distance.
Related, is there any good way to get suggestions to the engineers working on the software for things like this? Other than posting here hoping that they do read them occasionally?