A lot of them do. My wife's VW beeps an alert if you're too close to the car ahead of you. It might be that it only activates above a certain speed.

I think it will also back down the cruise control (if set) if it detects that you are gaining on the car ahead. That might be MILs Toyota though.

I learned the "two second rule" in Driver's Education 45 years ago and generally follow that. Nothing more annoying than having the car behind you riding your bumper.