Shoofin

I drove a car down to FL for a customer, a Black Sapphire/Beige 328i coupe. Basic car, had Premium, heated seats and automatic. So last Thursday night I ventured my way down to FL with my wife. I took my Garmin Nuvi 660 Navigation system with me, even though FL is practically a straight shot down I-95. I'm cruising at anywhere between 80 to 90mph most of the way, and happend to tap the nav screen to go to one of the settings to show all the details of the trip. Smack in the middle of the nav screen is my current speed, which at those speeds is about 5 to 6mph slower than the car's speedo is showing. I'm sure that this is known to most of teh euro snobs (hey, my wife's car is "only" an X3), but it was pretty new to me. On the flipside, the PT Cruiser convertible we picked up from Ft. Lauderdale Intl Airport I used for the weekend was showing the speedo to be slightly faster than the GPS, but not by much, about 1 to 2mph faster. Oh yeah, we got from Brooklyn, NY to Miami, FL in somewhere between 17 to 18 hours, stopping only for gas and the occasional pee stop..

That is all. Carry on.

cM3go

5%-6% variance

Infamous425

yeah theres a thread about this on the e90 forum

yohan81718

i think that's normal for any car... tire wear, tire pressure and etc can differentiate your speed from speedometer slightly as well.. but if you maintain a steady speed, what you read from GPS is dead accurate

Zippee

Remember that GPS is calulating on straight line point to point and does not account for up and down hill, side to side, etc..