speedo off anyone? - M5POST

nugent · 12-02-2012, 11:44 PM

anyone else think their speedometer is off? mine seems to be about 5mph higher than the actual speed I'm going according to GPS. any way to check and adjust this?

stealth.pilot · 12-02-2012, 11:58 PM

Quote:

Originally Posted by nugent

anyone else think their speedometer is off? mine seems to be about 5mph higher than the actual speed I'm going according to GPS. any way to check and adjust this?

Yes it is about 3mph high. It is deliberate.

You can change the setting to actual speed via coding.

nugent · 12-03-2012, 12:10 AM

Quote:

Originally Posted by stealth.pilot

Quote:

Originally Posted by nugent

anyone else think their speedometer is off? mine seems to be about 5mph higher than the actual speed I'm going according to GPS. any way to check and adjust this?

Yes it is about 3mph high. It is deliberate.

You can change the setting to actual speed via coding.

Thanks! I'll add that to my coding to-do list along with tire pressure numbers and rear drl's.

cairo · 12-03-2012, 03:25 AM

Mine seems pretty accurate. We have a lot of those signs that displays your speed here and it has always matched the HUD

xDrive35i · 12-03-2012, 02:43 PM

European cars tend to exaggerate speed slightly. Up until the moment you learned that, you thought you were an undefeated speed demon.

Tire pressures and rim size have a negligible effect on speedo readout. The engineers build this cushion in so that even if there are variables out of your control, there's no way you can sue the company for an inaccurate speedometer.

Make sure when swapping for winter that you buy rims and tires with a total rolling radius equal to factory spec.

jphughan · 12-03-2012, 02:48 PM

Yes, speedos read slightly high because it's illegal for them to read even 1% slow. Switching to a different tire size would definitely affect your readings, but not enough to be important at highway speeds. That really only comes into play if you're on the track gathering telemetry and really want to know your exact speeds, but in that case you'd be getting speeds from GPS anyway. I don't know whether BMW calibrates the speedometer differently depending on whether you ordered 19" or 20", but if not I suspect they calibrate for 20" because in that case switching to 19s means you'll be going slower than the speedo says.

nugent · 12-03-2012, 03:16 PM

Quote:

Originally Posted by jphughan

Yes, speedos read slightly high because it's illegal for them to read even 1% slow. Switching to a different tire size would definitely affect your readings, but not enough to be important at highway speeds. That really only comes into play if you're on the track gathering telemetry and really want to know your exact speeds, but in that case you'd be getting speeds from GPS anyway. I don't know whether BMW calibrates the speedometer differently depending on whether you ordered 19" or 20", but if not I suspect they calibrate for 20" because in that case switching to 19s means you'll be going slower than the speedo says.

makes sense. thanks.

mpresiv5 · 12-03-2012, 03:52 PM

i thought the car is limited at 155mph, my HUD hit 165mph and then i felt the limiter kicked in. can the calibration be 10mph off at top speeds?

LAKEOM5 · 12-03-2012, 03:54 PM

Nope, board shorts for me.

jphughan · 12-03-2012, 04:21 PM

Quote:

Originally Posted by mpresiv5

i thought the car is limited at 155mph, my HUD hit 165mph and then i felt the limiter kicked in. can the calibration be 10mph off at top speeds?

Yes, error margins can be up to 8%, which would be even more than a 10 MPH difference at those speeds.

12-02-2012, 11:44 PM	#1
nugent First Lieutenant Drives: f10 m5 Join Date: Apr 2011 Location: san francisco Posts: 305 iTrader: (0)	speedo off anyone? anyone else think their speedometer is off? mine seems to be about 5mph higher than the actual speed I'm going according to GPS. any way to check and adjust this? __________________ e92 m3 6MT, RS4 6MT, S4 Avant 6MT, WRX 5MT, Corsica
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12-03-2012, 02:43 PM	#5
xDrive35i Lieutenant Colonel Drives: 2011 X3 35i Join Date: Feb 2011 Location: Chicago Posts: 1,503 iTrader: (0)	European cars tend to exaggerate speed slightly. Up until the moment you learned that, you thought you were an undefeated speed demon. Tire pressures and rim size have a negligible effect on speedo readout. The engineers build this cushion in so that even if there are variables out of your control, there's no way you can sue the company for an inaccurate speedometer. Make sure when swapping for winter that you buy rims and tires with a total rolling radius equal to factory spec. __________________ 2001 Audi A6 Allroad 2.7T (C5); 2005 Audi A6 4.2 Quattro (C6); 2005 BMW X5 4.4i (E53); 2008 BMW 535xi Sports Wagon (E61); 2011 BMW X3 xDrive35i (F25); 2009 Audi A4 3.2 Quattro Prestige (B8)

12-03-2012, 02:48 PM	#6
jphughan Colonel Drives: 2011.75 M3 E92 6MT Join Date: Mar 2011 Location: Austin, TX Posts: 2,168 iTrader: (0)	Yes, speedos read slightly high because it's illegal for them to read even 1% slow. Switching to a different tire size would definitely affect your readings, but not enough to be important at highway speeds. That really only comes into play if you're on the track gathering telemetry and really want to know your exact speeds, but in that case you'd be getting speeds from GPS anyway. I don't know whether BMW calibrates the speedometer differently depending on whether you ordered 19" or 20", but if not I suspect they calibrate for 20" because in that case switching to 19s means you'll be going slower than the speedo says. __________________ 11 M3 E92 Le Mans \| Black Nov w/ Alum \| 6MT \| Premium 2 \| Convenience \| 19" \| EDC \| Prem Audio \| Moonroof \| BMW Apps \| Vorshlag Adjustable Camber Plates \| StopTech Street Perf Pads \| Castrol SRF Fluid \| ModMyNav.com rear camera

12-03-2012, 03:52 PM	#8
mpresiv5 Private Drives: F10 M5 Join Date: Jun 2012 Location: Maryland Posts: 57 iTrader: (0)	i thought the car is limited at 155mph, my HUD hit 165mph and then i felt the limiter kicked in. can the calibration be 10mph off at top speeds? __________________ 2013 M5 Alpine White / Black Ghost EWB, Flying Spur, SL550, CLS63, Cayenne S

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12-03-2012, 03:25 AM	#4
cairo New Member Drives: F10 M5 SG Join Date: Nov 2012 Location: Alberta / British Columbia Posts: 20 iTrader: (0)	Mine seems pretty accurate. We have a lot of those signs that displays your speed here and it has always matched the HUD

12-03-2012, 03:54 PM	#9
LAKEOM5 Second Lieutenant Drives: 2013 M5 Black Sapphire Join Date: Apr 2012 Location: Lake Oswego, Oregon Posts: 288 iTrader: (0)	Nope, board shorts for me.