On my trip back from Portland to Seattle. I noticed something. I doing a speed of 80 MPH according to my spedometer with the cruse control on. I re-set the average speed on the computer. Now the needle never moved but the average speed read 75.4 until I changed my speed.

I know there was a thred awhile back about having a difference in actual miles per gallon and the computer MPG. In that thred the MPG was high and the milage was low or something to that effect.

I wonder if this is where the actual difference is? Being that the spedometer is registering 4.6 miles faster than the computer.

Any comments?

 

I did EXACTLY this same thing yesterday morning, and was actually going to post on it too! I found a 4.6 (basically estimated it as 5mph) difference with the speedo registering faster. I had the cruise set to hold the speedo-measured speed at 90 and then reset the computer. It registered a steady 85.4mph.

One is clearly off...my guess is that the speedo is fast. Not at all uncommon in cars in general, and is something I think I've read about on MCO or the other site.

So now I guess we know that the folks who were posting pics of their speedo reading 130mph were REALLY only going 125.6 mph.

 

Same thing here... Set the cruise at a speed, re-set the avg. speed (even several times to "clear" it) and the two never match... Maybe that's another reason that MINI won't add the Actual speed to the Tach. computer read out... I still think having the actual speed available on the Tach. computer read out would be a nice option...Even if they are different! Oh well...

Motor on.... Paul

_________________
Paul830

 

Do you believe that the 5 mph higher speedo reading vs. the trip computer is linear across the range or decreases at lower speeds? (Wondering if there is a k-constant used in the trip computer's algorithm.)

Also, if you tried it at 60 mph, who's correct: the speedo or the trip computer?

These are things we MCOers lose sleep over.

SMKKVK

 

as a related question...
how do you actually reset the computer to show average speed?

peace,
d

 

Make sure that "Avg Speed" is showing on the display, and then press the computer selector button until the display clears. Same procedure resets miles-per-gallon when you have that function selected on the computer display.

Of course, Dennis, in your $40K MINI, I'd expect that you can get some sort of remote control that'll do this

 

>>Do you believe that the 5 mph higher speedo reading vs. the trip computer is linear across the range or decreases at lower speeds? (Wondering if there is a k-constant used in the trip computer's algorithm.)
>>
>>Also, if you tried it at 60 mph, who's correct: the speedo or the trip computer?
>>
>>These are things we MCOers lose sleep over.

I think the computer is more accurate. Haven't done any real testing, but based on observation of some of those "Your Speed" roadside radar units (which of course could be inaccurate as well), I've observed the speedo reading high.

 

The speedometers are designed to read faster than your actual speed to comply with european laws. I know that there is at least one thread on mini2 that goes into details about what the acceptable difference between the speed indicated on the speedometer and actual speed.

The consensus is that the computer is more accurate when tested the way listed at the beginning of this thread.

 

Find one of those unmanned radar signs that tell you how fast you are going... There are a few around town here in Louisville. But, they may be off also. The difference between average and real will never be the same. How long did you keep the average going at your 80 speed? Did it come closer the longer you keep it at 80? Or am I just talking out of the side of my head mathematically? Because I am still waiting for mine

 

I kept the 80mph for about 15-20 miles. When I first re-set the Avg s. it veryied only a point or 2 down. Meaning if I remember right, it was like 75.6 and went down immediatly and then stayed there.

Of course I should mention that the speed limit was 80mph...

I think?

 

Average and real speed will be exactly the same if you start recording your data points for the average at speed, and don't alter your speed, which is what was done here. However, the computers seems to be more accurate than the speedo. As everyone has said, speedos have some innacuracy in them, and those inaccuracies will always be on the high side. They are designed this way to avoid lawsuits from people who get speeding tickets while their speedo says they are at/under the limit.

PigLick

 

>>Average and real speed will be exactly the same if you start recording your data points for the average at speed, and don't alter your speed, which is what was done here. However, the computers seems to be more accurate than the speedo. As everyone has said, speedos have some innacuracy in them, and those inaccuracies will always be on the high side. They are designed this way to avoid lawsuits from people who get speeding tickets while their speedo says they are at/under the limit.
>>
>>PigLick


It seems the spedometer is 5% optimistic. Do the math. The OBC calculation is accurate.

retroom

 

>>Do you believe that the 5 mph higher speedo reading vs. the trip computer is linear across the range or decreases at lower speeds? (Wondering if there is a k-constant used in the trip computer's algorithm.)
>>
>>Also, if you tried it at 60 mph, who's correct: the speedo or the trip computer?
>>
>>These are things we MCOers lose sleep over.
>>
>>SMKKVK
>>
>>

I've noticed the same thing with my MC, CVT. The computer reads lower than the speedo. I think it's linear having noticed about the same difference at low speeds (40 MPH) and high speeds (90 MPH). I asked the dealer about this discrepancy and they said its within the accuracy of the instrumentation. Before the Mini, I had a BMW 325e with an onboard computer and the computer speed indication and speedo indication matched within a mph or so.

 

On my MCS, I've noticed that around 50mpf is when the speedo starts to read high. I have the Nav system and a nice feature is the limit button. When I'm doing 80 on the speedo I push the limit button and it tells me 75. I tested it recently to find the point at which the speedo starts to read higher. Again it's around 50. The Nav system tells me 45. But any lower than that and it's pretty accurate.

 

On my MCS, I've noticed that around 50mph is when the speedo starts to read high. I have the Nav system and a nice feature is the limit button. When I'm doing 80 on the speedo I push the limit button and it tells me 75. I tested it recently to find the point at which the speedo starts to read higher. Again it's around 50. The Nav system tells me 45. But any lower than that and it's pretty accurate.