My speedo shows 2mph faster than what my Garmin GPS shows. I have tested the gps in other cars and it is spot on. I also drive by those Police
radar signs and once again there's a 2mph difference. what could cause this? My car is an 04 525i with 138 rims. It probably originally had the 15s. Could that be the prob? Is there a solution? I'm concerned my mileage is off as well because of this.

 

https://5series.net/forums/index.php?showtopic=30490

https://5series.net/forums/index.php?showtopic=51111

 

Thanks. Is the mileage tied to the speedometer? Is the speedometer in the "hidden menu" more accurate? Bummer when it comes to warranty and lease terms.

 

with a 12K/yr lease you are alloted approx 32 miles/day

if you drive 32 miles a day at approximately 65 miles an hour

it comes out to about 30 mins of driving.

30 mins of driving/day @ 65 mph is a little over 1 mile a day extra @ a 2 mph overage.

1 mile a day for 3 years = roughly 1100 miles.

1100 miles = 110 dollars at lease turn in. cheaper then fixing the problem

if my math is off, i did it in my head and rounded to make it easier. i would presume your average speed is probably half that. if that is the case, predict turn in penalty to be roughly 55 bucks.

this is assuming you go over your miles. if you go over more, figure you can attribute 55 bucks or so of it to your speedo problem.

 

just about every single car on the road if off by somewhat. Fast you go the more it is off. Tire pressure can change speedo accuracy

 

My car isn't leased so my concern is the original (now expired) cpo and maintanence warranties (about to expire) The funny part is the dealer gave me a chevy cobalt rental pos and that things speedo was dead on.

 

BMW can make it dead on but I think they purposely make it off by 2 MPH... almost every single BMW I can think of including MINIs that I've tested it is off by 2mph. I heard it was better that way... so people cant complain that their speedo was wrong if they get a ticket. Its off in the wrong direction.