Cruise control function

[geoff]

During the 12K mile service this week, the dealer gave me an '08 Boxster tip loaner. My wife has an '05 Carrera tip. When the cruise control is set and driving down a relatively steep grade at 50+ MPH, both the Carrera and Boxster tip transmissions automatically downshift to maintain speed instead of accelerating. My '08 Cayenne S never downshifts as it picks up speed on a downhill grade with the cruise control set. I realize the Cayenne is fundamentally very different from the Boxster and Carrera, but should the Cayenne tip transmission automatically downshift to maintain speed with the cruise control set? Or isn't it that smart?

[mudman2]

it should brake

During the 12K mile service this week, the dealer gave me an '08 Boxster tip loaner. My wife has an '05 Carrera tip. When the cruise control is set and driving down a relatively steep grade at 50+ MPH, both the Carrera and Boxster tip transmissions automatically downshift to maintain speed instead of accelerating. My '08 Cayenne S never downshifts as it picks up speed on a downhill grade with the cruise control set. I realize the Cayenne is fundamentally very different from the Boxster and Carrera, but should the Cayenne tip transmission automatically downshift to maintain speed with the cruise control set? Or isn't it that smart?

[geoff]

it should brake

It should logically, but doesn't. Nobody else has chimed in to say theirs does brake. Next dealer service, I'll see if I can get a Cayenne loaner and do a comparison.

I asked on the PCA tech section, and Peter said "One of the things here is to know that what Porsche has put in the Cayenne is a Japanese transmission and control unit where as the Boxster and Carrera use German systems. Somewhere the two don't have the same philosophy and maybe that will change in the future... "

More fuel for the Cayenne bashers, but we still love driving the Cayenne. It's no Carrera or Boxster, but for an SUV, it still drives quite nice :)

[Bill_SoCal]

Interesting...we use our cruise control fairly frequently on both Cayenne's. I've never noticed the vehicle to pick up speed on a decline. I drove my V6 from San Diego to Texas a month or so ago and was pleased with the cruise control. I don't know that we've every tried it on a really steep grade. I have it on my list to check out...

Bill B)

[bigbuzuki]

Tried mine on a downhill slope. There was no braking or transmission downshift to control the selected cruise speed.

[geoff]

Got an '08 Cayenne (V-6) loaner today when I took the Carrera in for a final warranty item. Driving back through the canyons, with the cruise control set, the Cayenne kept accelerating on the downhill stretches instead of automatically downshifting to maintain speed. So yes, the Cayenne tip/cruise control operates fundamentally different from the Boxster or Carrera :o