Most liked posts in thread: Intentional speedometer miscalibration?

:cornut: Some of the Nurses that I used to work with said that unbuttoning the top 2 buttons of their blouse often worked. Give it a try DaveO.:yikes::yikes:

Jason

 

That's exactly what I try and tell the police officer but it does not work for 20 mph over.

:aureola::devil::lol::lol::lol::lol::lol:

 

This has been the case in every European car I've owned. Read up on UNECE regulation 39 if you'd like a detailed explanation.

--Matt

 

This:

In many countries the legislated error in speedometer readings is ultimately governed by the United Nations Economic Commission for Europe (UNECE) Regulation 39[3] which covers those aspects of vehicle type approval which relate to speedometers. The main purpose of the UNECE regulations is to facilitate trade in motor vehicles by agreeing uniform type approval standards rather than requiring a vehicle model to undergo different approval processes in each country in which it is to be sold.
European Union member states must also grant type approval to vehicles meeting similar EU standards. The ones covering speedometers [4] [5][6] are similar to the UNECE regulation in that they specify that:
The indicated speed must never be less than the actual speed, i.e. it should not be possible to inadvertently speed because of an incorrect speedometer reading.
The indicated speed must not be more than 110 percent of the true speed plus 4 km/h at specified test speeds. For example, at 80 km/h, the indicated speed must be no more than 92 km/h.
The standards specify both the limits on accuracy and many of the details of how it should be measured during the approvals process, for example that the test measurements should be made (for most vehicles) at 40, 80 and 120 km/h, and at a particular ambient temperature. There are slight differences between the different standards, for example in the minimum accuracy of the equipment measuring the true speed of the vehicle.
The UNECE regulation relaxes the requirements for vehicles mass produced following type approval. At Conformity of Production Audits the upper limit on indicated speed is increased to 110 percent plus 6 km/h for cars, buses, trucks and similar vehicles, and 110 percent plus 8 km/h for two- or three-wheeled vehicles which have a maximum speed above 50 km/h (or a cylinder capacity, if powered by a heat engine, of more than 50 cm³). European Union Directive 2000/7/EC, which relates to two- and three-wheeled vehicles, provides similar slightly relaxed limits in production.


Read more: speedometer: Definition from Answers.com

Dave

 

Just another data point...my 2012 MCS is off by ~3mph at 70'sh speeds (car speedo compared to my GPS readout), was consistent throughout my recent 2200 mile round trip to south Texas.

 

:cornut:My Margi's(08 R56 BRG MCS/JCWm) speedometer reads 3mph faster than I'm actually going. Down here in Texas(unless it's a holiday weekend) one usually must be doing 5mph over the speed limit prior to being stopped. On our 70mph highways(we also have 85mph highways) I set the cruise control at 75mph and the smokies don't even blink. I also remember reading about MINI adding 'fudge factor' to the speedometer but I can't remember where.

Jason

 

I've seen several reports that only the speedometer reads high, not the odometer. Both are controlled by digital electronics so they are separately adjustable. The speedometer is set high from the factory but can be adjusted with NCS Expert software (that accesses the car's computer).

 

What DneprDave said...

Discussed a LOT in the early days of this Forum. Minis tend to be a % or two higher than other cars, and even changing from a 205/45/17 to a 215/45/17 it's still a few % high. Unusually, the speedo may be off, but the odo seems more accurate. Try it on a long highway slog against the mile markers... or your GPS...

 

This topic comes up about once a year or so. There are lots of threads about it, hence it is well known.

There is an article from Car & Driver dated April 2002 that I always refer back to when this topic comes up.

Speedometer Scandal! - Feature - Car and Driver

 

^^^^ Good article. I dropped to 195/50-R15 and my speedo is off by 10 mph. I have to use the GPS, or the rev counter to know how fast I'm going.

Jim

 

:cornut: 3mph-Me Too!

Jason

 

My speedo reads 3mph high with 205's and 2mph high with 215's as compared to my GPS. The error is consistent across the board.

Kent

 

My MINI's speedometer reads 4km/hr higher than my GPS.

 

Just to add my $.02 worth, ours is 4 mph optomistic at a real 60 mph as compared to gps, roadside radar and stopwatch. Odometer is correct as per road milage markers. When it's time for service I plan to bring it up with the dealer to see if they do anything.