genevagear

I drive a manual transmission 2018 Base Cayman 718. On a downhill with cruise control set the car will control speed to keep it from rising above the set speed. It feels like the car is braking but I doubt it. I don't think it is engine braking because if I switch off cruise control, on the downhill, the car will accelerate. Anyone know how the speed is being limited and controlled?

r553

I believe when going downhill the cruise control uses fuel cut off. My Cayenne does this and it is fairly effective in the mountains.

Antee

Check out page 96 of the owners manual. http://www.porscheownersmanuals.com/...Cruise-control It states that it does active braking and on the same page states it can't always follow the set speed for manual cars.

I own a 981 PDK so I'll see what happens when I do cruise control in manual mode it down shifts and engine brakes in auto. 981 only has mentions of active braking for adaptive cruise control so this may be a standard thing for 718's now.

JCtx

Regular cruise never uses the brakes, and as noted, it says so in the manual. It engine-brakes when throttle is fully released indeed... but if speed picks up more than a few mph (typically 5, but don't remember if our manual specifies that), it just cuts off. I always drive in manual mode on my PDK, so cruise doesn't downshift, but it might in auto mode. With manuals, it's the same as PDK manual, with the only difference maybe being that we might be able to downshift without cutting cruise, but with a manual, the moment you engage the clutch, it disengages, so no go there. Bottom line is use engine-braking when going downhill, even if cruise disengages. Engage again when flat. For the record, I hardly ever use cruise, especially on sports cars. And yes, active cruise uses the brakes, and in many newer ones, down to zero now (you just need to nudge the throttle to reengage after a stop of more than a second).