Speedometer Error
My C300 4matic reads 105 km per hour when I am travelling at exactly 100 km per hour, as displayed on my Garmin GPS - a 5% error. At a true 60 km per hr, the speedometer reads 63 km per hr - 5% again; and at an indicated 130 km per hr, I am only going a true 124 km per hour. My last car - '04 Volvo XC70 - had no discrepency vs. the Garmin, and I have checked the Garmin against my SLK and wife's Odyssey - both were within 1 to 2% error.
I'm assuming this means my odometer is racking up km's 5% higher than actual (I'll hit the warranty mileage limit at 95% of true mileage) and my gas mileage is also being reported 5% on the optimistic side. Has anyone else checked their speedometer for accuracy? |
Interesting ... I wonder how a non Garmin owner can measure this ... I'm at 4000K's already, granted I drive from Newmarket to Toronto daily, but would love to know if it's accurate
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...Mile markers? Just an idea im kinda confused and tipsy... and tired... night all. Now to walk up my flight of stairs.
-Mike:y |
do you have larger wheels or anything to that effect? i know that could cause the speedometer to be off. i have a garmin too, maybe i should try your theory out. ill update when i do
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Originally Posted by Ted in Toronto
(Post 2592056)
My C300 4matic reads 105 km per hour when I am travelling at exactly 100 km per hour, as displayed on my Garmin GPS - a 5% error. At a true 60 km per hr, the speedometer reads 63 km per hr - 5% again; and at an indicated 130 km per hr, I am only going a true 124 km per hour. My last car - '04 Volvo XC70 - had no discrepency vs. the Garmin, and I have checked the Garmin against my SLK and wife's Odyssey - both were within 1 to 2% error.
I'm assuming this means my odometer is racking up km's 5% higher than actual (I'll hit the warranty mileage limit at 95% of true mileage) and my gas mileage is also being reported 5% on the optimistic side. Has anyone else checked their speedometer for accuracy? however, I have passed many speed checks on the side of the road, and they all agree with my speedometer on my c350 |
Originally Posted by marakbai
(Post 2592065)
Interesting ... I wonder how a non Garmin owner can measure this ... I'm at 4000K's already, granted I drive from Newmarket to Toronto daily, but would love to know if it's accurate
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Speedometer error and odometer error are not synonymous - the odo, I suspect you'll find if you check it against a measured distance marker, will be within 1% or less.
We once had a '96 Acura RL [aka Legend] which had a ridiculous 7% speedometer error, but whose odometer was absolutely spot on Don't assume you're accumulating KMs 5% faster because the speedo is that far off - check the odometer for yourself. And, incidentally, our C300 Lux has speedo readings that are within 1-2% of measured markings and radar readouts. |
My speedometer is overstated the speed by 3% with the "plus-sized" (205/60R16 instead of 205/55R16) winter tires... This is comparing with the GPS (Garmin) and radar display in my neighbourhood. When the speedomoter indicating the car is going at 103km/hr, actually it is going at 100km/hr
I would imagine my OEM all season will be at least 5% off, also... |
I currently have OE tires and wheels and with a garmin nuvi navigation i get 1mph less on the nav. I hardly see a 2mph difference. I have not checked the kph difference, but i would think it would be the same.
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I have three radar signs that I pass occasionally. When I am driving about 45,the sign reads from 43-44.
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Originally Posted by sagar350z
(Post 4529776)
I currently have OE tires and wheels and with a garmin nuvi navigation i get 1mph less on the nav. I hardly see a 2mph difference. I have not checked the kph difference, but i would think it would be the same.
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Originally Posted by amdeutsch
(Post 4529903)
1 mile = 1.6 kilometer. Same? :smash:
:eek: Actually now that i think of it... yeah that didnt make sense.. anyways thanks for the correction. :y |
I get about 4-5 kph optimistic reading on my 204, at 100kph, versus a Tomtom.
I understand most speedos are optimistic, to reduce the likely hood of drivers trying to blame the manufacturer for marginal speeding offenses. I don't there is any similar effect on the the odometer. |
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