Hello y'all! I'm new to this so I'm still trying to get the hang of this.

I bought a Cayenne in last September and I noticed about 2 months ago that the digital speedometer is kinda off, like if I'm going 30, it will say 33. I checked it with the neighborhood speed meter- both my other cars had no problems. Anyone else have this issue or is it just me? Also, when the car is idling, I feel like the whole car vibrates after idling for awhile? I'm bringing it to the shop next week, but still there's that nagging itch that wants to know. Other than that, i love my pepper!

Any info/ experiences is much appreciated!

 

I think this is normal. Check out this article . . . http://www.caranddriver.com/features...ometer-scandal

. . . here's the executive summary 3rd and 2nd from the last paragraph . . .

The European regulation, ECE-R 39, is more concise, stating essentially that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70). Never low. Not even if somebody swaps a big set of 285/35R-18s for stock 255/45R-16s.

There's your explanation of high-reading European speedometers, with the highest readings on Porsches and BMWs that are most likely to lure owners inclined to fool with tire sizes. Of course, only the speedometer must conform. Trip computers are free to report average speed honestly. Try setting your BMW or Porsche cruise control and then resetting the average-speed function. Unless you've screwed up the tires, the trip computer should show a nearly accurate reading. Even General Motors, whose domestic speedometers are the best, must skew its readings slightly high on vehicles exported to Europe.

 

Every single one of our cars (5) is off, always showing faster than real speed tested against GPS. I was told this is how the manufacturer designed it to be.

The Ferrari being the worst offender, off by at least 7 mph.

 

Don't have a Ferrari so i can't compare but our (3) recent BMW's are by far the worst. I'll have to look for the specs they consider acceptable but it's grater than 10% off.

My ('06) Cayenne actually reads 1 mph low at 75 mph (GPS checked) since I put the new wheels/tires on 18 mos. ago. Doesn't bother me but the BMW errors drive me nuts.

 

ALL Cayennes are OFF. This IS WORSE on a 2011/12 cars vs previous years. ALL GERMAN cars are OFF (PORSCHES, BMWs, MBs and etc.). All 2011/2012 Cayennes are too high at speedometer indication by 3mi/h at speeds of 30-40 mi/h and by 4-5mi/h at speeds of 70-80 mi/h.

It have become even WORSE during the last 2 years. It used to be better in the 1990s...

...many, but not all Japanese cars are precise at the speedometer vs real speed...

 

Found the BMW "acceptable error" info on one of the BMW forums.

I have no idea what Porsche's acceptable error specs are these days.

 

Great information. I've never checked my Cayenne since it has navigation but my 997 is doing just what has been posted at highway speeds - registering 3 mhp faster than my Garmin says I'm going.

Question - Does the odometer remain accurate or is it calculating mileage at an accelerated rate as well?

 

In this day & age, seems there should be some capability for the car's GPS to be able to self correct or adjust the speed indicator if one could put it in some kind of "adjustment" mode or else have a way for the dealer to do it.

 

Porsches already do this and I believe the Odos are pretty accurate. On my turbo over a 20,000km service interval the GPS in my Kenwood unit was about 90km different from the odo on the dash. The discrepancy in speed reading is, I believe, designed-in to remove any possibilty liability from the manufacturer in speed enforcement cases.

 

After reading this thread last night, being curious, I took my Garmin GPS with me to work today in my Boxster. The car's speedometer was exact to what the GPS was showing. I will test this on the Pepper maybe tomorrow...

 

My understanding is that Porsche deliberately sets it higher by 10% more than the actual speed.