Have my 2009 MCS for a week now and it seems that the speedo it pretty optomistic. I'll be on the road doing 80mph(speedo reading) and cars are going past me at a pretty good clip. It doesnt feel like 80 thats for sure and others in the car say the same thing. Anyone else have this also? Wondering if I should inquire with my dealer to check calibration.

 

It varies by tire size and inflation.

You can "calibrate" yours against a GPS or the measured-miles on many freeways. - by which I mean figure out the percentage difference your tires on your car are off from accurate.

The dealer will almost certainly not adjust the speedo for accuracy, so you get to spend the rest of your ownership muttering to yourself - "Let's see, the speedo reads 70, so 4% less than that means I'm really doing 67.2 actual mph...

 

All MINI spodometers read fast. All BMW spedos read fast. Some people say that all European cars are this way. HOWEVER, the odometers are correct. I have run GPS and mile marker tests that confirm that the odometer is spot on. The spedo reads fast by design. There has been dozens of threads on this.

 

I've always been under the impression that the odometer gets its measurement from the same speedometer gear in the gearbox. Does MINI/BMW do it differently? It used to be that if your speedo was off by x%, so was your odo.

 

When spedometers and odometers where both driven with a mechanical cable it was true that if one was off both were likely off. That is not the case with cars today which are electronically and computer driven. Believe me, I have checked my odometer at least 5 times with GPS and mile markers (over stretches of 10+ miles at a time). It is spot on even though my spedo reads 63 when going 60.

 

Yep - the speedo is off by 3mph everyday!

 

Correct, I found the same thing, about 3-4 mph off (higher) than actual speed at 65 mph. I am assuming my gps that has also has a speed indicator is correct.

 

I've been in new MINIs that were as much as 7 mph off at 70 mph, dealer says that MINI says unless it's more than 7 off, they won't fix it. I think this is ridiculous, and it's not common to German cars - my '04 Audi is spot on according to my Nuvi, and a MBZ SLK I drove was also. I don't know why BMW does this, but I speculated that it might have been to offer better MPG numbers, however if the odo is right - that shoots holes in my theory.....

Whatever their reasoning, it's just plain wrong. Would they give us fuel gauge that always reads 1/2 full? A temp gauge that always reads normal, even when overheating? it's just as wrong to have such an innaccurate speedo, especially when it can be made to read correctly.

I do not understand them on this...........

 

Speedo reading-5%+=true mph.

 

Well, I can cross this from my list of things to ask about.

Mine reads +3 over the GPS as well as all the construction signs that display speed in work areas. Actually, the signs are pretty good according to my GPS.

I had already decided to leave it alone. It might help keep me out of trouble.

 

By repeated timings using measured mile and stopwatch, my speedometer is 3 mph fast from 35 to 70 (haven't timed it faster or slower). Verified by GPS readings (which according to measured mile timings is right on.) And, using measured mile markings over a distance of 40 miles on an interstate, my odometer was only 40.1 miles. By the way, my wife's 535xi's speedometer is dead on, according to measured mile timings. One of the first things I always do with any new car is check the accuracy of the speedometer.

 

My GPS and mile marker/stopwatch timing drills indicate I'm indicating 5mph higher than actual from 60mph up to 80. Haven't tested above 80.

At 50mph it reads 53.

 

QFT. I am always comparing my radar detector's GPS speed readout with my speedo, and found this to be the case. It is affected by percentage, not a set mph addition. For example, at 80mph, your speedo will be less accurate than at 15mph.

EDIT: I will verify this, so take what I said with a grain of salt.

 

Mine reads aproximately +6% or 20=19, 30=28, 50=47, 70-=66, 80=75, etc..

The ScanGauge's MPH is accurate without calibration adjustment (which could be entered for 'odd-size' tyres) and it reads from the MINI's OBD Port, so the car's computer does know the true speed.

 

The wheel/tire size and inflation will affect the car's reading by some percentage, which will be constant at all speeds. The car does not "know the true speed" in any way - if the odo reads correctly, it's a coincidence.

Which is to say, if the speedo reading is off by 4%, then that's 1mph too high at 25mph indicated (actual 24mph), 2mph high at 50 (actual 48mph), 3mph high at 75, etc. The odo variation may be different than the speedo, because they don't want you to get a ticket, but have to report mileage accurately by law.

If you change wheel/tire size to a different percentage different from true speed, then the odometer reading will shift by exactly as much as the speedo, and might read too high or too low on the reported mileage.

 

When going past one of the highway departments big radar things in a construction zone my speed-o-meter said 50mph and the radar on the big radar machine was also saying 50. I was not over or under at all. When they had one at the school it said 20 and my speedometer said 20mph. My car is a 2009 JCW. I do have 38 psi nitrogen in the tires. My speed-o-meter needle always matches my MPH readout on my tach. I guess when my tires wear down the speed-o-meter will be off a little but I do not think it will be by much.
Ronnie

 

I've read on another thread on the speedo accuracy issue is that under German law, the builder can be fined if they are found to produce a car whose speedo reads higher than actual speed. So the speedos are designed to read low or at best correct if the largest tires available from the manufacturer are used.

 

I set cruise to 4 over and seem to be keeping up "With the Joneses"

 

I was actually wondering that tonight. I went through a neighborhood that had a digital sign showing my speed. My odometer read 31 mph, the sign said 26mph. I used to have 16", now I have 18" maybe it the way thinner tire?

 

i found that my speedo was 5mph higher than my actual speed of travel by my GPS unit. just confirmed this over the weekend when i drove by one of the radar detectors that posts your speed. it read 30 while my speedo was at 35. GPS confirms the same at higher speeds as well from 50-70, it is the same throughout. now that i know, when im the only car on the road, i jus cruise at a lil over 5mph above the posted limit... so the cops cant pull me over for driving too slow lol.

 

This is the speedo VS GPS!

 

I have two different GPS units. Both say that my Speedometer is fast, by 3-5MPH.

I did not accurately account for my odometer, but it looked to me that it was .1 mile faster then my GPS...

This will add up miles on my car pretty fast if it is true and I am not certain I like that idea...

 

Hey, Mom, look! 240kph with one hand on the wheel and one eye paying attention! Wanna try?

 

Apologize,
But it was TWO hands OFF the wheel.... to avoid Camera shake, you know!

 

I've steered like that on occasion. Takes a car that turns you on.