[Klamalama]

Have owners done a check on their speedometer's accuracy? My Q50S AWD is just 1 mph slow. I think that's very good.

My Lexus RX350 reads 4 mph slow, typically.

My ex BMW also read 4 mph slow, until I changed the 35 profile rears to 40 profile. Then it was only 1 mph slow.

I'm using Waze, an iPhone app, to check against.

 

[Rayz]

was your RX and BMW bought used? if that's the case, it's possible those owners could have put on something different.
using waze to track speed will be good for those that want to install bigger aftermarket wheels.

 

[SteinyD]

I think mine is overstated by 15-20 mph. It always says I'm going 80-85 mph. That is impossible when the speed limit is 65 mph

 

[Q50Aggie]

Mine is over by about 2mph. There is a speed display on a street near my house. Speed limit is 35mph, and when my speedometer on Q50 says I am going 35, the speed display says I'm going 33.