I have found that while driving in heavy traffic at highway speeds ... rather than going from gas to brake all the time - I set the cruise control at the speed of the slower cars, proceed to drive faster than every one else. Then when encountering a slower car in front of me - simply removing my foot from the gas introduces pretty good engine braking within a second or so.

My Wife prefers this gentle action as opposed to me hitting the brakes.

 

8 cylinders do slow the car pretty well and I think all models by now have "hill descent" - a program that will do everything to keep set speed including downshifting.
In such situation my wife prefers that I start passing.