I swear mine is wrong.
I go down the highway showing 73mph and old ladies in Crown Vic`s are passin me.
I go 40 mph <posted speed> and seems to be everyone is jockeying to get around me.
Has anyone with a GT had this problem?
Has theirs been corrected?
Did the Dealer do anything?

 

The speedo reads 2-3 mph fast in my 06 GT, verified by GPS. I think that you may just be running into all the lead foot people out there.
Any before anyone else says it, You have a Mustang, Use it!

 

You can check it on the interstate by travelling an indicated 60 mph and timing the milemarkers...one every 60 seconds if it is indeed actually 60 mph and the milemarkers are accurate. Do it for 5 -10 miles and take an average. It would be helpful to pick a stretch of highway that is fairly level so the cruise will not fall behind on maintaining the speed on hills.

I hope this helps.

Tony D

 

You could flag down a local police officer and have him check you with his radar. I've done it before myself, and I've checked other people with my radar when I'm on duty. Sometimes it is funny how far off the speedo's really are on some cars.

 

Its a common problem on these cars:

http://forums.bradbarnett.net/showthread.php?t=44125
http://forums.bradbarnett.net/showthread.php?t=31016

 

I`ve got a appointment tomorrow at the Dealer to replace the rear window tint , and look into the speedometer issue. If that is not fruitful , I may have to tackle a DPS and get him to clock me at different speeds <if they will>. Not too many flat stretches in Austin where the traffic won`t be a problem. Thanks Y`all.

 

I think the easiest way is to have a friend in their car keep pace with you while using your cell phone to communicate with them. Of course, you could always do about 70 in a 45 zone and have a law enforcemnet official write the number on the ticket. At least it will be verified by radar and you won't even have to ask.