The cable is the Durametric in the Porsche world and it is actually from the same group that does the BMW one.

I actually traded some emails with the guy that makes the Porsche one and the issue is that Porsche has been making their systems a PITA to hack for a long time. Functions are spread all throughout different modules in the car and they use various encryption methods to make it more difficult. I believe it was the 996 he said he had to pull open the brake module and hack the hardware to finally crack its encryption.

In 13 they changed things again so (as Greg mentioned) all the cable can really do at the moment is read codes and reset your service intervals. They are always working on it though.

More annoyingly is that even the Porsche techs apparently can't disable the alarm beep on the 13s.

 

Hopefully someone can figure how to code newer Cayenne's. Dealers (even Bimmer dealers) go by the rule books so they're not the most helpful. The Bimmer crowd can code all sort of things.

 

I figured this out a few weeks ago. When you have an active navigation routing there is an additional "PCM" menu that is available in the multi-function display in the dash. That menu has the option to turn the speed limit display on/off.

 

I don't recall that you need active navigation routing for that function. I think they are always available (and if you pick it, the little speed sign showing if it has been coded for the road you are on--i.e. you can see that little sign go away and come back when you get off a major road on to a smaller road and then back) whether navigating routing or not. You pick and choose the line items you want to see on that screen which is really nice. I played with mine till I got want I wanted specifically battery voltage as I have a little refrigerator in the back.

 

N - My 2013 does exactly as you described.

 

The double horn noise is infuriating, sounds like a rental car. My Pan Turbo had the chirps, my Pan GTS and CD both have horns, hate those horns so much!

As for the speed limit display, you can turn that on/off in the settings, when traveling on unknown roads I turn it on; it is annoying otherwise so around home I turn it off. It seems to only show main interstate speed limits and state roads, doesn't show local speed limits.

 

The 13 I picked this week has the chirp. Ya never know with Porsche, seems like they change things every month on the same model year.