BenTheRighteous wrote:Call me cynical but that's always my suspicion. Manufacturers clocking their speedo's too high because it makes warranties expire prematurely, without anyone noticing.
I've owned several vehicles with high speedometers compared to GPS. I've owned none that were too low. If it really is just an accident, it's awfully fishy that it's an accident in one direction only.
How much speedometers are off by are NOT always the same about by which their odometers are off by.
There are also reasons why they're off. See links at viewtopic.php?p=177842#p177842
. The Priuschat link may no longer point to the right post due to a software change over there. You'll want to look at post 17 at a few that follow.
Also, what's displayed by the speedometer and odometer can be affected by how worn the tires are. From https://www.tirerack.com/tires/tiretech ... techid=177
When the GPS indicated exactly 100 miles had been traveled while the vehicle was equipped with new 12/32" deep tires, the vehicle's odometer registered 99.4 miles. When the vehicle was then equipped with another set of the same tires shaved to 2/32" of remaining tread depth, the odometer indicated 101.0 miles. While the 100-mile test distance didn't change, essentially the vehicle's odometer overstated the distance traveled by about 1.5% when equipped with the worn out tires.
And, there can be differences in the # of revolutions per mile on different makes and models of tires even though they're all the same size. They list 3 tires of the same size: the OE tires on the 08 Prius vs. 2 others and the revs per mile range from 855 down to 843.
As shown above, there are slight differences between the tires' published diameters, tread depths and tire revolutions per mile. However, if a tire rolls fewer times per mile than the tire it replaces, the vehicle will again actually be traveling farther than is indicated by the odometer. Calculating the influence of the different tire specifications on the vehicle's odometer would indicate the Yokohama AVID TRZ would travel .6% farther than the Goodyear Integrity, while the General Altimax RT would travel 1.4% farther.