cruse control quirks

... and after decades of driving just 4-cylinder engines, I was quite surprised by the strength of CC engine braking in my dad's V-8 Jeep.

 

True, but low-compression motors (typical in most motor vehicle) is a very ineffective way to reduce/control speed on downgrades. That the Prius has regenerative braking is a big plus. Otherwise, you'd have to rely on the brakes, and that cooks your pads and brake fluid if it's long and steep enough.

 

Not true. There are virtually NO really low compression engines in use anymore.
Higher compression generally means better fuel efficiency.

If the engine has computer controlled valves, they can be manipulated to give even more engine braking when needed.

 

My bad. I'm not up on newer cars and trucks. Most cars (I'm used to) do not have "high-compression" motors like motorcycles. Most motorcycles have effective compression braking because you let off the throttle and you drop speed fast. My pickup truck and most cars I've driven coast (even manual transmission) when you let off the gas, they don't slow down that much.