the speedo in the Mini or the sign they put up on the side of the road that flashes your speed and is supposed to slow you down? My speedo read about 4 miles per hour faster than the sign. I guess if the sign is more accurate that means I can go 4 mph faster than the posted limit and be doing the limit. Niice.

 

I suspect the sign is more accurate. Lots of variables with the speedo reading - and I've read that German makes typically read a little fast (I think it was a Consumer Reports article).

 

I checked my speed against GPS and found that GPS was slower by 2mph that what was shown on the speedometer. I thought I was going 80 mph, but really on doing 78(GPS). I will stay within the 10 mph forgiveness supposedly given by the MAN. I thought the speedometer may be calibrated for 15 inch tires and I have 17 inch to account for the difference. Let's motor.

 

Related question..... my digital speedo on the tach reads about 2 mph slower than the needle in the speedo. And no, this isn't a point of view issue, I leaned over so that my eyes were even with the center speedo (not at an angle).

-- Jay

 

The radar sign will be more accurate, but only if you're the only car in view - we've got a local one that swings wildly when there are multiple cars.

I've check my speedo(s) with the GPS - the MINI is within 1 or 2 mph, but other cars can be off by as much as 5mph, depending on speed.

 

Or, the size of the tires. If you have swapped tires from what was on the car from the factory, and the replacement tires are not within the same dimensions (diameter and/or revs/mile), you will also see variation in speedometer (and odometer) reading. It can get as simple as wear of the tire as well. When new, the tire can be spot on accurate, but at 25% remaining tread, the indicated speed and distance can be off.

 

The SIGN, no question

 

I'd trust the sign. I haven't checked my MINI's speedometer against the mile markers and a stopwatch, but I have on a previous BMW (speedo was 7% high) my Triumph bike (10% high) and my Chevy truck (spot on).

 

The speedo we see is designed to read high. Inside the "secret" computer menu on the speedo (go to mini2 faq for more info on how to access it), there is one that shows you "actual speed", its about 3km/h slower when the speedo (and the digital speedo on my 05's tach) shows 100km/h. I've checked it against one of those radar sign thingy in a construction zone, and it seems like the "actual" speed show in the secret menu is correct.

 

my 325i was about 5-10 pecent overestimating speed (which is certainly better than underestimating), my bmw bike was 10 high, and the rental gm cars i checked displayed very close to actual speed.

haven't checked the mini yet, maybe saturday on our way to jersey

 

My understanding is this is not uncommon because German laws have very tough penalties for speedo's that indicate a slower speed than actual. I have a boxster as well as my mini and it is common that the speedo is high by as much as 5 mph on Porsches. In protecting themselves, German car manufcturers speedo's usaully report a few mph high.


Bob

 

going back to the original question about which is more accurate...

i don't think it really matters... the cops go by the sign or their radar so the whatever that shows up on the sign/radar is their 'accurate' guage.

 

Road and Track tests speedometer error, and found that Porsches are generally pretty accurate until over 100mph, when they start to get wildly optimistic up to +20mph. They must have had some irate customers whose cars couldn't reach the same top speed as the magazine test cars...

Some discussion on the other board: http://www.mini2.com/forum/showthread.php?t=30333