Speedometer Question

[joshuaalbert]

After constantly being passed on the highway by minivans and dump trucks I thought it was time to test my speedometer. My wife and I drove side by side and we found when the Boxster said 70 MPH, the other vehicle said 64 MPH. Has anyone else ever experienced this problem and/or is this a typical problem with Porsche?

I have only owned the car for about a month and absolutely love it! However, when I feel the need for speed (as is often the case), I would like to accurately know how fast I am going.

[ohioboxster]

My speedo is 4 mph fast so at 64 mph on my speedo im going 60mph. This was confirmed with radar. No not a ticket issue.

joshuaalbert, how do you know your wife's car is accurate?

Mine is 3 MPH fast, which is the normal factory setting. Your dealership can dial this in to be more accurate.

[deliriousga]

The factory setting comes out to about 3-4mph fast. When I plugged in a OBDII reader and watched the readings, I was going 4mph at idle sitting in the garage so Porsches don't just "look" fast when they're sitting still.

[velvet_jones]

Mine is about 4 MPH slow according to the CHP radar trailer.

[RandallNeighbour]

So someone spell this out for me. If I've got the cruise set at 65 in a 65 mph zone and a cop shoots his radar at me, am I really going 4 mph over the limit or what?