Hi everyone. I'm new to minis - just got a 2011 MC the other day. I was wondering if speedometer errors are normal on minis? When the speedo says 70, I still have people flying by me on the highway. I'm going to take the GPS with me tomorrow to compare it, but it seems to be reading about 5mph high. Just wondering if anyone else has noticed this....

Thanks in advance.

 

yep, noticed this myself.

 

OK I'm gonna do the GPS test tomorrow and let you know. Can't get much more accurate than that.

 

I expect you will find something like a 4MPH error at around 65 (i.e. actual speed of 61ish when you test w/ GPS or GPS enabled phone. Error should be a pretty consistent percentage relative to indicated speed.

 

There is about a 3 MPH difference. Wouldn't call it an error as it is there on purpose. Mine reads right at 3 MPH slow so I just set my cruise a little high to compensate and motor on. I keep up with traffic and don't attract unwanted attention. This issue has been discussed here in the past.

 

mine is +3, but I'm not running the OEM diameter for tires so that's no surprise

it might have spared me a time or two, who knows?

 

mine reads 5mph fast so if in going 75 speedo, im really only going 70. my only concern is, am I putting more miles on my car because my speedo is reading fast? I do know that you cant believe the MPG since the speedo is off. The MPG is about 3-5 mpg off as well. is there anyway i can fix this because i truthfully dont like it

 

Thanks for the responses guys. I wonder why the discrepancy?

 

I can't find the threads on this right now, but i know that it's been previously discussed that the BMW tolerance for the speedo is -0/+5 mph or thereabouts. This appears to be constant and not a percentage of speed.

If you're not running the oem tire diameter, then it fiddles with it even more and you'll have a grand old time watching your odometer not match up with your actual distance travelled.

 

You probably are not adding miles faster than actual. However, the only way to verify is with a GPS.

I was able to get my speedo spot on when I went with 215/45-17 tires, a little larger than stock. 70 on the speedo is 70 on the GPS (also calibrated my SGII so I have double check).
However, now my odo is about 3% low. (also verified by GPS and SGII) So I am only showing about 97% of the miles I actually put on. For most people this is an acceptable error.
So while your speedo my show higher speed than actual, the odo may be accurate.

Also, I have seen lots of complaints on this board about speedo reading high on MINI's, but all cars read somewhat high from the factory.

 

After reading jonabad's comment I remembered a web page I'd stored away in my dusty archives. This might help if you aren't rolling EOM tires.

http://www.miata.net/garage/tirecalc.html

Hope it helps.

 

It's a 5% error that BMW incorporates on all their vehicles. Their motiviation in doing this is not certain, but common sentiment is that they do not wish to held liable for traffic fines due to instrument errors.

 

My historical understanding is if caught in the US, a big fine is owed if they underread the speed, but none the other direction. Logically it will be enforced by NHTSA type rules codifying it. So guess what the manufacturers do? Recent posts on the same topic suggest the Euro legal overlay drives similar behavior.

 

Hmmm... let's put some numbers to it and see who gets the advantage:

If the speedometer is reading 5% fast (at typical speed) you're recording "more" miles on the odometer than it the vehicle really has... so, 5% of 50,000 miles is 2,500 miles. This means their warranty is only 47,500 miles.

Is this a big deal? Doesn't sound like much but if your Mini does have problems in which the 50,000 does apply and they claim you're over - here's your argument!

Now how about the inaccuracy of the fuel gauge....

 

They arrange it so the Speedo reads fast, but the Odo is spot on. So the warranty really is 50,000 miles.

 

It's a pretty consistent 4mph, no matter what speed I'm doing. That's ok, I can deal with that as long as the odo is correct!

Thanks to all for the info and happy motorin'

 

so why would the MPG be wrong? say i go to the gas pump and put in X gallons, take XXX miles divided by XX gallons and i come up with a different number and always a lower pen and paper number. example if my MPG says 32 my pen paper figures come out say 30. also, i reset the MPG every time i fill up.

another thing i guess if the miles were reading high i should essentially come up with a higher pen and paper number. so maybe the miles are right and it just doesnt know how many gallons it uses..i dunno!!!!

 

If you use a OBD reader like a scanguage, you can see that the ECU shows a different speed than the speedo, so the Odo is spot on.

 

I never said anything about the mpg being incorrect. Just the speedo reading high.

I just re-read your post and now see you're saying your mpg's are inconsistent. I hope mine is correct, since I just got home from a road trip and averaged 43mpg according to the computer!

 

You'll find several reasons that your speedometer is going to read high. First, in Europe, the manufacturers can be fined for speedos that read low. So naturally they throw in a little bit of an error to avoid this. They will also have this error set for the largest tire/wheel combination that they have. If your tires are smaller, you get an even bigger error. My Justa Cooper seemed to have a combination of a fixed, 2 mph error, plus a 3% error. I now have tires that are 3% larger than stock, so that error has been nullified. But there is still the error of about 2mph that's consistent at all speeds. My odometer now reads about 2.5% low.

I remember a few yerars ago someone taking a bunch of supercars, running them at top speed and clocking them with radars to see which one had the most accurate speed claims. The Euro-trash cars were horrible -- some being 15 mph or more slower than what the speedos said. The US cars were the most accurate.

 

I'll check that out but it seems very unlikely..

What's their "excuse" for not having the fuel gauge accurate? I know the tank is convoluted but in this day and age they could physically determine the volume at depth increments of perhaps 1/8" and have a microprocessor use those findings to show the volume in the tank. Microprocessors are very inexpensive nowadays - less that $0.50 for one that will do this job!

 

An indicated 130 MPH is actually 126 on my Garmin GPS. This is with 215/45/17 tires.

 

My '03 tends to read about 3MPH faster that it is actually going.

 

Why unlikely? It's already been explained in this thread that regulations require speedos to never read low and are allowed to read a certain amount high, so they mfgs split the difference to have them read a little bit high. But the odometers have a different spec that it centered around zero error, so they calibrate them to be more/less accurate. This makes the two inconsistent but it is done this way to meet regs.

They already have sufficient processing power in the body computer - the issue is the cost and trouble to develop the calibration curve to correlate the sensor reading with the fuel level. It's not terribly hard to do so, but at the same time, the sensor has pretty wide tolerances to begin with and this is not a mission-critical instrument. And more errors creep in as the car is not perfectly level, both front-back and side-to-side. As long as the last 1/4 tank or so is reasonably consistent and gives the driver adequate warning of low fuel, the instrument has done the job it is designed for.

These cars are built to a price. Consumers neither demand nor are willing to pay extra to have a super-accurate fuel gage so they don't spend the money on it. Simple as that.

- Mark

 

Well.....I'm glad I did a search today. I've only had my R56 for a week and I replaced the 16" wheels/tires with 17". Today I put my GPS in the car for a small road trip and notice the speedometer was reading 4 mph faster. I thought it might be because of the wheel swap, but I guess not!

Chuck