I am really looking forward to the ACC on my IS250. My current Volvo's cruise control does not have ACC. If cruise control is active and the car in front slows down, I tend to creep closer, hoping that the car in front will speed up again, rather than braking and kicking out the cruise control.
I know, not smart.
With ACC activated, that problem goes away as the IS250 slows automatically to keep a minimum distance behind the car in front if it slows and then resumes if the car in front speeds up or changes lane. Top idea if you ask me