[skyking]

It does go back quite a ways, that beneficial effect. I wonder if a technically savvy guy could make a Cruise control input coupled with a laser rangefinder. Get in behind a good truck, engage. Now if he slows without braking, you still get that safety buffer in case something happens, instead of trusting your eyes only.
If he speeds up past your original set point, oh well. Find a better truck
We have all crept up closer than we wanted in times like that.
Maybe some indicator lights.