"Engine braking" isn't just letting the engine spin down at 0 throttle. Propper engine braking, aka "Jake brake", is letting the engine spin at 100% throttle but zero fuel input (and some valve trickery). This lets air in to be compressed, releasing it before the down stroke of the piston. No car does that. It is a separate installed system on trucks. It can be almost as powerful as the engine. In a car, it could handle all but emergency braking.
I have on my manual 15-year old diesel bmw very much an engine brake. It breaks quite well compared to neutral which seems to like to go on forever, and actually indicates proper consumption.
On highways and motorways, I rarely need to use brake at all. Of course, being a sensible driver helps (in contrary to what many people expect from me when they see the car and expect yet another immature aggressive driver)
Maybe not exactly the same, but the B mode on hybrid cars sound similar.
When you are driving down a large hill (e.g. on a mountain) eventually the battery will become fully charged, so you can't use regenerative braking anymore. To provide some resistance so you aren't effectively driving in neutral, the car will spin the engine at high RPM without supplying any fuel (I'm not sure how this works in terms of lubrication, as I understand the fuel provides this too?). You can also engage B mode which does this at an earlier stage, so have more control without having to use the brake when driving down steep hills (like engaging a lower gear).
London hybrid busses do the same thing, as they come to a stop you can hear the engine spinning at high RPMs.
> Engine braking occurs when the retarding forces within an engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes.
> The term is often confused with several other types of braking, most notably compression-release braking or "jake braking" which uses a different mechanism.
But when you see a sign saying "no engine braking" it refers to the jake brake, not down-shifting in a car. (It's a long trademark story over the use of "jake")
https://en.m.wikipedia.org/wiki/Compression_release_engine_b...
When you hear a truck making popping noises like a machine gun, that's the Jake brake in action.