Speedo Accuracy?
 

So I was on a road trip this weekend, and a friend was following in his BMW. Late night driving, rural roads, cruise set on 73 (speed limit 70). My friend calls and says can we slow down he doesn't want to go 80. Apparently, with my cruise on 73, his cruise is 79. Consistent for many miles - not just catching up.


I have no reason to believe my speedo is off and neither does he. How does one check to see if it's right?

Use a GPS. From what I've read here it's not uncommon for the speedo to be off from the factory. Mine wasn't, but it was after I put on larger tires.

Use your GPS - smartphones with GPS apps and or handheld GPS units will show your actual speed.

Best way to check is buy or borrow a GPS that displays speed [garmon, Tomtom etc and compare readings or find a straight stretch of hiway with mile post markers set speed at 60 and time between markers. My 2015 with stock wheel and tires is spot on with the GPS at all speeds

I wonder if he should use a GPS... :thumbup:

I'd use a GPS.

So no question that the BMW's speedo was accurate?

It's another trick BMW uses to make the mpg look good. Sort of like how Ford counts the gallons used.

Looks like bmw is over estimating ;). Needs to seem fast lol

I know on my 13 st when I put winter wheels and tires on, which are considerably smaller, the computer automatically adjusts the speedo for the small wheels. If this tech is in a focus I'm sure it's in these f150.