How "OFF" is your speedometer?

[EIGHTLUG]

I'm currently running the factory DUNLOP RFTs. Air pressure @ factory spec. My speedometer reads 3+ MPH more than GPS (2 Phone apps and one Garmin) @ highway speeds (75-85). Anyone else experiencing this? Is there a fix?

[mikikuki7]

Originally Posted by EIGHTLUG

I'm currently running the factory DUNLOP RFTs. Air pressure @ factory spec. My speedometer reads 3 MPH less than GPS (2 Phone apps and one Garmin) @ highway speeds (75-85). Anyone else experiencing this? Is there a fix?

Yes, about the same 4mph. I use radar, and my radar picks up 72 and I'm driving 75-76mph.

[Zipforia]

Same here. 4mph.

Z.

[MysticBlue]

That's totally normal and expected. Most cars read a little high, especially European cars. They tend to be 2% to 5% high. Speedometers only have a certain amount of accuracy across the manufacturing process and regulations say they cannot read low, so they shoot for about 3% high, and the spread ends up being about 2% to 5%. My M3 is about 4%. The analog speedo on my X5 is about 3% high, the digital on the heads up display is about 2%. All compared to GPS, which is very accurate.

[hyde]

Originally Posted by MysticBlue

That's totally normal and expected. Most cars read a little high, especially European cars. They tend to be 2% to 5% high. Speedometers only have a certain amount of accuracy across the manufacturing process and regulations say they cannot read low, so they shoot for about 3% high, and the spread ends up being about 2% to 5%. My M3 is about 4%. The analog speedo on my X5 is about 3% high, the digital on the heads up display is about 2%. All compared to GPS, which is very accurate.

I am confused.
Does speedo show slower than actual speed or faster?

1st post says speedo indicates slower but you are saying speedo should indicate faster.

[MysticBlue]

Originally Posted by hyde

I am confused.
Does speedo show slower than actual speed or faster?

1st post says speedo indicates slower but you are saying speedo should indicate faster.

No, we're all saying the same thing. The speedo reads high. The speedo reads faster than you actually going.

[batmanken]

I was gonna ask the exact same thing lol, my speedometer always seems to read high, but I don't know by how much.

[Barbja]

My E70/E71 were about 3mph high. For 95% of my driving, it probably kept me out of trouble so I'm good with it. For the other 5%, that 3mph buffer wouldn't help me at all.

[Kzang]

This is the case for all BMW's.

[hyde]

Originally Posted by Barbja

My E70/E71 were about 3mph high. For 95% of my driving, it probably kept me out of trouble so I'm good with it. For the other 5%, that 3mph buffer wouldn't help me at all.

Great. It will not keep me out of trouble anymore, I need to erase this thread from my memory and totally ignore this. Knowing that I am going 3mph slower is not helping me now..

Originally Posted by MysticBlue

No, we're all saying the same thing. The speedo reads high. The speedo reads faster than you actually going.

Ah, you are right, I really need to stop browsing forums too late at night...

[rlemek]

Who looks at what speed they are going? ;-) This is however great news as now i can actually go 90 in the 75 and be good hahaha... "but officer... the forum told me that BMW speeds are off a bit"

[opasha]

Originally Posted by rlemek

Who looks at what speed they are going? ;-) This is however great news as now i can actually go 90 in the 75 and be good hahaha... "but officer... the forum told me that BMW speeds are off a bit"

haha at the officer comment

[MattBianco]

Don't make me produce a link, but I recall reading (paper) when the Miata (MX5) was first released about 25 years ago that Mazda deliberately calibrated the speedometer to be at maximum legal error (5%?), to make the drivers feel like the car was performing better than it actually was. I think that first generation also had a feature in the speedometer that made it produce a small bounce when hitting zero. Again, as a part of the "experience".

Now, can I advertise the X5 for sale in a few years as : 2015 X5, 57k miles (odometer reads 60k), Mineral White, .......?

Sounds like we need slightly higher profile tires to get it right . For those with 19" wheels, 255/55 r19 seems to bring speed closer to reality: http://tire-size-conversion.com/tire-size-calculator/

[hyde]

So when 0-60 times are posted, is it actually 0-57?

[MattBianco]

Originally Posted by hyde

So when 0-60 times are posted, is it actually 0-57?

If you measure yourself, probably yes. As disclosed by BMW, probably not.

[MysticBlue]

Originally Posted by hyde

So when 0-60 times are posted, is it actually 0-57?

No. I assume you are talking about magazines and such... Those tests are done with very accurate instruments. Same with manufactures claims. If someone is using their speedometer, then they must be using a handheld stopwatch. That wouldn't be very accurate regardless of the accuracy of the speedo.