Speedometer accuracy
 

Has anyone noticed, or questioned the accuracy of the speedometer? My wife is convinced something is wrong. She commutes daily, and said that tons of people are flying by her while she is going 75....and says she used to go 73 in her Ford Escape and not many people blew by her.
We are going to do a 2 car tandem test soon, but thought I'd ask everyone else. Thanks.

Have her try using her phone with Waze to compare ...it'll show your speed... Google does also, I think...it's 2019, no need to do a tandem drive/drag race... At least not for this reason. Would still be fun though!

No problems. Have used it with Waze and both agree on speed. One thing to watch out for is Waze does a bit more averaging so when speed changes it is slower to "catch up" but if you turn on cruise control and/or keep speed consistent they should match up.

Checked with Waze, speedometer is about 4 to 5km off (faster than the actual speed), which, for some weird reason, is the default for almost all cars in Europe. You would think that a car with that kind of technology would be able to display the exact speed...

Wow! That's a bit much. I've read that most makers calibrate their speedometer down so that you cannot sue them if you get pulled over for speeding because your speedometer read X.

It seems to be the default now for all European cars. On my McLaren the speedometer reads about 7% high. So when I'm doing an indicated 70 I'm actually doing 65 mph. Amusingly, the car's GPS navigation shows a GPS based (accurate) speed on the Nav screen which contradicts the dashboard speedo. I have asked the dealer if they can adjust it to be more accurate and they indicated that by (US) law they can't make any changes and it was set that way on purpose to comply with EU regulations.

I've tested this on an app called Speed Box, and on my E1 the speedometer is off by 0.5 mph