Someone mentioned in the middle of a post recently that they found the MINI's speedometer to be quite inaccurate at higher speeds (80 mph) - up to around 3-4 mph off. They mentioned that this was a notorious BMW flaw, so it didn't surprise them. Greatgro, was it you maybe?

Just curious if anyone else has noticed or verified this. Does it read higher or lower than actual speed, and how can I check it, other than finding one of those flat measured miles on the highway and using a stopwatch and cruise control?

Not that 3-4 mph would make a huge difference if one got pulled over for doing 80+ in New England...

 

Hi,

I've taken the following out of a UK mag...

True Indicated on speedo
30 31
40 41
50 52
60 62
70 73
80 83
90 93
100 104

Hope this helps a little

 

Sackman's article from england is just one example - and that speedo is very close actually compared to others.

I read in a letter to the editor in the Roundel (BMW CCA magazine) between 12 and 24 months ago that the speedos on BMWs were allowed actually vary from indicated speed by +5% to -10% from the factory in germany and ONLY if they were outside this range would it be corrected under warranty.

So, at an indicated 80mph in my 2002 BMW 525i I could actually be going anywhere from 72 to 84 miles per hour - that's a dang big range and it would be allowed within the factory specs.

(For the record - based on GPS my actual speed is 76 when I am indicated 80 on the speedo, but the trip computer registers 79 as average speed if I reset it when I'm at an indicated 80mph - this is in the mentioned BMW 525i)

I don't know what the MINI's accaptable % of deviation is.

So keep in mind next time you're pulled over and the officer asks if you know how fast you were going you only really know your indicated rate unless you have a GPS unit sitting on your dash.

(and even then... speed is all relative, right? If it was a roaming cruiser (i.e. K band from a rolling unit) it is calculated as a difference of their 'calibrated' speedo and the radar detector indicated speed... so now you've got the fudge factor of TWO speedos... 'calibrated' speedos are still +/- to a certain tollerance and the faster you're going the bigger the possible fudge factor for both cars... at an actual speed of 80 your speedo could say 76 and his 82... causing a disagreement)

Anyway, back to work.

-dq

 

There's a speedometer on my Cooper?!

I've noticed the engine-roar meter mounted on the steering column and the intensity-of-smile gauge in the center of the dash. Please help, where's the speedometer?

_________________
Indi Blue Cooper w/ Black top & mirrors, sport seats and Prem. Pkg. Christened "Ringo".

 

A few years ago, FL passed a law that said you couldn't recieve a ticket for less than 5mph over the limit, because of calibration issues with personal spedometers...

 

I really don't think there is a car made with a completely accurate speedometer. Trust your tach.

 

while playing with a hand held garmin gps unit on my drive back from myrtle beach, i verifiyed that my speedo was 3-4.5 mph off, and they only get worse the faster you go. I have read that most speedometers are calibrated to be on or fast, not slow(imagine what that could cause), but playing with the gps unit, you see the real deal, and most cars i have tried it in are off a few mph.

_________________
Tearing apart the finest corners Chicago has to offer in the Lquid Yellow MCS!

 

>>>>So keep in mind next time you're pulled over and the officer asks if you know how fast you were going you only really know your indicated rate unless you have a GPS unit sitting on your dash.
>>
>>(and even then... speed is all relative, right? If it was a roaming cruiser (i.e. K band from a rolling unit) it is calculated as a difference of their 'calibrated' speedo and the radar detector indicated speed... so now you've got the fudge factor of TWO speedos... 'calibrated' speedos are still +/- to a certain tollerance and the faster you're going the bigger the possible fudge factor for both cars... at an actual speed of 80 your speedo could say 76 and his 82... causing a disagreement)
>>

Nice try, but on moving radar, the radar clocks the police vehicle as well as the target, then calculates target speed from that and the closing or separating speed. The officer should compare the radars indicated patrol speed to his calibrated speedo to make sure they're relatively the same, but the radar will be the more accurate (+ or - 1mph).

Anyway, except for "calibrated" speedometers (police vehicles, etc), which must be kept calibrated yearly, any vehicle is going to have a 3-5 mph speedometer error.

signed,
your friendly motorcycle cop and police radar instructor.

 

I don't know about BMW AG, but BMW motorcycles are set so that the speedos read intentionally higher. I was taold about this when purchasing frrom the dealer. The resoning is a marketing one: BMW drivers get fewer tickets. Or at lest that is the premise. I don't know if that is official policy, mind you, but I can certainly see the merit in it. Kinda like setting your alarm clock to be just sleightly faster than the clock at work.

 

How much does wheel size alter the accuracy? Are the speedos set for 15" 16" or 17" wheels? Just wondering...

Denny

 

>Nice try, but on moving radar, the radar clocks the police vehicle as well as the
>target, then calculates target speed from that and the closing or separating
>speed. The officer should compare the radars indicated patrol speed to his
>calibrated speedo to make sure they're relatively the same, but the radar will be
>the more accurate (+ or - 1mph).
>
>Anyway, except for "calibrated" speedometers (police vehicles, etc), which must be
>kept calibrated yearly, any vehicle is going to have a 3-5 mph speedometer
>error.
>
>signed,
>your friendly motorcycle cop and police radar instructor.

I wasn't stating it as an excuse - just something people should be aware of. In many jurisdictions a poorly calibrated speedo gets you absolutely no leeway. And in other jurisdictions (particulary deep south) the officer's word and judgement can be enough in a court of law to get you a ticket - no radar even needed.

Of course the radar guns must be calibrated to a +/- tollerance and then there is a fudge factor based on angle of attack, etc., etc.

There are MANY points of calibration andin each a +/- tolerance. Just don't take your speedo (or tach for that matter) as a perfect reflection of reality.

-dq

 

The motorcycle cop can probably confirm this, as I'm sure they get slightly annoyed...

But I've found the best way to avoid a ticket (on the highway at least) is to simply buy a CB radio, put it on channel 19 (breaker one nine can I get a coooopy, when I get one for the mini, my call name will be "Crazy Brit&quot, and the truckers will frequently give updates on the sly location the "smokeys" are hiding. But don't spread that word, only for us MINI owners. Nice lil' secret. We don't want EVERYONE knowing how to have a better chance at avoiding a ticket. Or you could just not speed... but I went from Cleveland, Ohio to San Francisco, California and back without one problem from the police.


You agree, beauguste3?

 

>>while playing with a hand held garmin gps unit on my drive back from myrtle beach, i verifiyed that my speedo was 3-4.5 mph off, and they only get worse the faster you go. I have read that most speedometers are calibrated to be on or fast, not slow(imagine what that could cause), but playing with the gps unit, you see the real deal, and most cars i have tried it in are off a few mph.



Could this possibly be a way that they improve their profit margin? Could this error simply be a way for them to make money?

 

>>The motorcycle cop can probably confirm this, as I'm sure they get slightly annoyed...
>>
>>But I've found the best way to avoid a ticket (on the highway at least) is to simply buy a CB radio, put it on channel 19 (breaker one nine can I get a coooopy, when I get one for the mini, my call name will be "Crazy Brit&quot, and the truckers will frequently give updates on the sly location the "smokeys" are hiding.

Yeah, the redneck telephone has been bein used for that forever. it's good stuff, really comes in handy, also, I've seen on GPS modules in cars where you can get them programmed or somethin er nother that'll let you SEE where all the cops are, it picks up frequencies from somethin er nother and they'll actually show up as little DOTS (or whatever else you decide, i've seen dots, pigs [lol], donkeys, pretty much anything you could imagine.) I'm not 100% sure as to where you could get this or how much it would cost, but I'm sure if you contacted a dealer who installs them they could help you out.

NOTE: this isn't the little hand held thing that gives your coordinates, I'm talkin about the little screen that has driving directions and all the streets and what have you.

 

>>But I've found the best way to avoid a ticket (on the highway at least) is to simply buy a CB radio, put it on channel 19 (breaker one nine can I get a coooopy, when I get one for the mini, my call name will be "Crazy Brit&quot, and the truckers will frequently give updates on the sly location the "smokeys" are hiding. But don't spread that word, only for us MINI owners. Nice lil' secret. We don't want EVERYONE knowing how to have a better chance at avoiding a ticket. Or you could just not speed... but I went from Cleveland, Ohio to San Francisco, California and back without one problem from the police.
>>
>>
>>You agree, beauguste3?

Whatever slows people down...I don't like writing tickets, but I hate working wrecks more...
(BTW I'm off the bike because I got T-boned by a kid)

Naturally, those driving MINIs will be above average drivers in every way

 

>>I wasn't stating it as an excuse - just something people should be aware of. In many jurisdictions a poorly calibrated speedo gets you absolutely no leeway. And in other jurisdictions (particulary deep south) the officer's word and judgement can be enough in a court of law to get you a ticket - no radar even needed.
>>
>>Of course the radar guns must be calibrated to a +/- tollerance and then there is a fudge factor based on angle of attack, etc., etc.
>>
>>There are MANY points of calibration andin each a +/- tolerance. Just don't take your speedo (or tach for that matter) as a perfect reflection of reality.
>>
>>-dq
>>
I know what you meant, I just don't want people thinking that the patrol vehicles speedo has anything directly to do with what the radar reads...
We all like to drive fast now and then, lets just pick the right spots to do it.

 

::Wince:: T-boned on a motorcycle? Yeesh, I hope you recovered okay from that one...?

 

In the UK I use an Origin Blue - Click Me
Speed Camera GPS Device.

It displays current Speed and Direction of Travel..It can lock onto 10 satalites at the same time.

The Speedo calibration on my Cooper S is fantastic, and within 2-3mph even when reaching three figure speeds.

 

>>How much does wheel size alter the accuracy? Are the speedos set for 15" 16" or 17" wheels? Just wondering...
>>
>>Denny

The ACTUAL wheel/tire diameter DIRECTLY affects the speedo reading. But the manufacturer accounts for this with different wheel diameters (15, 16, 17) by changing the TIRE "aspect ration", which affects the "tire height". Thus, the TIRE OD for ALL of the different wheels should be "identical". In reality, the OD for the "same" tire size, but different vendors, varies slightly. But not even CLOSE to the 2" difference in WHEEL diameter (that's why the 17" wheel TIRES have 45% aspect ratios with a 205mm width; and the 15" wheel TIRES have 65% ratio; & 175mm width).

Is that CLEARER? (or muddier?)