All the cars I have had will not downshift for CC for engine braking. On my Subaru manually downshifting (the auto tranny in ‘manumatic mode’) I believe will disengage CC, for that matter the check engine light also will disable it 
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The only car that would do something like that is my Nissan Rogue which is a CVT, so not really downshifting - but is simulating a downshift. However it does that even without CC on a decent. So it’s not doing anything special for CC.
Sure, no reason they can’t use the nickname in commerce. And General Motors has a registered trademark on “Chevy”.
Thanks for enlightening me. Ignorance fought.
Poking around on google, it turns out that Jacobs Vehicle Systems actually has a form letter just for this (PDF warning):
https://parts.jacobsvehiclesystems.com/files/support/docs-pdfs/ordinance_letter.pdf
Officially know as Engine Brakes here (on the signage .vic.au). Also sometimes called Exhaust Brakes, and… air brakes … (by people who don’t know any better). Dunno who makes them here, but never heard of Jake.
Of course, too, if the sign said “Jake Brakes” and the truck had a competitor’s system, then maybe the trucker could fight any ticket he got.
I have heard of ‘Jake’ brakes here in the UK, but not for many years. Most manufacturers have their own exhaust brake systems with varying degrees of efficiency. None of them make enough noise to warrant a sign.
The last truck (proper 44-tonne articulated truck) I drove before I retired was fully automatic (two pedal) and I used to use the exhaust brake all the time. Since it is more effective with higher revs, the trick on a down gradient was to force a down change. From the vehicle owners POV, this is preferable to braking as it reduces wear on brake pads.
While it is often preferable, in some cases it’s critical. I think the UK doesn’t have many high-speed mountain roads, but here in the US, there are a number of interstate highways that pass through mountain ranges; the grades can be 6% or more and can descend for several miles. An 80,000-pound semi (“articulating lorry”) will not survive such a descent without using engine braking.
It’s a thing in California, at least for Caltrans (California DOT). In fact, Caltrans doesn’t like using signs advising against using engine braking, as you’re telling the driver not to use a safety system in their vehicle to control their speed, which then opens up liability claims should they crash. I tried putting some up once and was turned down by management for this reason.
Staff report
Thank you - I often wondered how they worked and why so noisy.
True for the UK, but the trucks are pan-European and there are some fairly hair-raising roads in the Alps and in Scandinavia.
I thin our signs are “Unmuffled Engine Braking Prohibited” in Washington.
As for cruise control, and modern Ford I’ve ever driven has kept its cruise control speed exactly where I set it. Old Fords, such as my 2004 Expedition, don’t actually let you set a specific speed, but rather, kind of tries to keep the vehicle at the speed I set it. It generally does okay uphill, but won’t aggressively downshift if it’s too steep. Downhill, aside from cutting the fuel supply, it will let gravity take over.
For any newer Ford where I can set a specific speed that’s shown on the IC, they will shift as necessary going up or down hill. The oldest example of this I can remember is the 2011 Expedition I had in Mexico. I drove it pretty much all over the country, including mountainous areas. It was set-and-forget.
These days I used the adaptive cruise control almost exclusively, which will engage the brakes. Sometimes this is very gentle, and I often worry that my car is making people that follow me think that I’m some nervous, old woman constantly tapping the brakes.
I have a newer car with adaptive cruise control and I’ve wondered a couple times if the brake lights are activated when the system slows the car down. In most cases it’s pretty gradual and it seems like it’s be overkill to activate the brake lights for just a 2-3 decrease in speed. Maybe the rate needs to be fairly rapid to trigger the brake lights?
Technically, I believe that regenerative braking would count as ‘engine braking’, since you are using the engine to slow down (although presumably almost completely silently). Although I guess if you want to be super picky, it is no longer an engine/motor at that time but a generator.