Thanks, Ken1784 for providing that very interesting document!

I am definately NOT a math wiz, but working thru the formula, using 40mph for indicated and 37mph for actual, converting to kph, as 64.37kph and 59.54kph respectively, seems to give me these results: (don't know how to make the "less than or equal to" symbol, so < will mean that in this post.)


0<(40mph-37mph)<0.1X37mph+4kph
0<(64.37kph-59.54kph)<5.954kph+4kph
0<4.83kph<9.954kph

4.83kph=3mph
9.954kph=6.19mph


0 < 3mph < 6.19mph

So...my speedo fits this rule....but...what does this rule realy mean? Any math majors out there that can explain this to us math challenged folks? (or at least me)

 

Previously, each country had their own regulations, for example Japanese regulation was -10% to +15%.
An impoted/exported vehicle had to modify the speedometer to meet the country's regulation.
It was stupid process to do such, then they, especially in EU, defined the worldwide standard regulation.

Ken@Japan

 

I just checked my speedometer & odometer with a Magellan GPS 315. The speedometer was low by 3 mph with cruise set at 70. The odometer was also low but by only 0.9 miles over a 61 mile trip.

Note: The Magellan GPS 315 is not a certified unit.

 

Are you saying that your car's speedo read 67 when the GPS indicated 70, or did the speedo read 70, (cruise set at 70) and the GPS indicated 67? The later is what most of us have experienced, I believe, and would indicate that your car's speedo is reading higher than actual speed.

Your odometer test shows virtually the same as mine, 1.5% low.

 

Jbollt: The speedo read 70 but the GPS read only 67 and the trip, according to the GPS, was 61.9 miles but the Trip B display was only 69.0 miles. Sorry about the confusion.

 

David, No worries, it can get very confusing..so your speedo reads higher than actual by 3mph, just like most TCH owners have reported. Thanks for clarifying, and doing the test with the gps.

 

I'm still hand calculating my FE, but at the bottom of my personal spreadsheet I am adding a one line calculation for "corrected FE" (with a 1.5% additional miles included in the hand calculation. It's over 39.5mpg! I had given up on even trying for 39 but I now have a new goal of maintaining the 39 level. It's interesting for me to find now that the Computer is actaully closer to the true FE than a hand calcluation. (0.3 mpg too high for the computer, 0.5 mpg too low for my hand calculations).

I can sleep now at night with this resolved

 

Just out of curiosity, since my speedo has been bang on with my GPS, I'm wondering if all of you speedo-challenged folks get e-mode past 42mph indicated then? Mine usually shows an ICE spin up at around 41mph.

 

Andy, just a quick observation....most (if not all) of the posts I am aware of with the speedo reading 3mph high have been US spec. But yet you mention the e-mode coming in at 41mph, not in kph. You are apparently in CANADA, with kph speedo. I wonder if the CA speedos are closer to accurate than the US spec ones? Japan uses kph i believe also.

 

I usually try to speak "American" for all my metric challenged friends on this forum. The ICE spins up around 65/66 kph. The speedo calibration is likely different. The Canadian model speedo tops out at 240kph whereas from pictures I see the US model speedo tops out at 230kph on the smaller inner metric scale.

I was just curious if the US model speedos are over-reading, if the discrepancy shows up in the emode - ICE spin transition speed as well...