Cayenne Diesel Cruise Control - Problem

[muzski]

Had my cruise control set at 30 yesterday and noticed on a downhill stretch (not particularly steep) the speed had crept up to 37!!! With a speed camera 200 yards ahead I had to brake but had I not, I think it would have continued to rise. I appreciate cruise control isn't going to keep it bang on 30 but more than a 20% variance and the chance of picking up a speeding ticket seems very, very wrong. I had noticed the previous day when it was set at 50 it had crept up to 57 on a slope.

I have spoken to Porsche and they want it in to investigate. Just wondered if anyone else had experienced this?

[dmcrobin]

Unless you have adaptive cruise, the system doesn't use the brakes to reduce speed, only engine braking, so rolling on down hill will increase your speed greater than engine braking will slow you.

[Flat6er]

^^^^^^^^^


This. Cruise is no substitute for common sense. Nor can the standard system overcome the laws of physics. Also, engine braking has been engineered to minimum levels to help reduce resistance and help the holy grail of mpg/co2.

Edited by Flat6er on Sunday 15th July 10:50

[Cobnapint]

I've used the cruise on my CD, but not on a steepish down hill slope.
I'm sure my old SLK 350 used to brake though, to keep the speed the same as the one you requested...