Speedometer off?
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Yeah, I've basically trained my brain to automatically knock a few mph off of what it says I'm doing. Construction zone limit of 55? Do 58 max. 25mph school zone? 27 max.
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9,156 Posts
Normal all vehicle Speedometer are like that. Not exact speed reading. Nothing you can do about. My Tom Tom will give a different speed reading, while the car. It’s Giving a Satellite speed. I can be driving side by side next to a Honda Civic, on the highway. I can see he’s digital speedo on the its dash. A different speed reading.
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Thanks. I may have to do something about my wheels soon anyway: I recently got the "Wheel sensors missing" message and I'm not sure what that's all about. When I got the low tire warning, I took it to a tire shop and they couldn't read the sensors but didn't have any clue about Smarts. My regular shop is much more knowledgeable so I'll see what they say.
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It's normal, all smarts do it to some degree! 
I've also asked some engineers about this and the consensus is that while the speedometer will read fast, the odometer should be actual.
Fun fact: Federal law says speedometers must be accurate within +/- 5 mph of actual at 50 mph. Most people misquote the law as meaning you can't design a speedometer that runs more than 5 mph faster than actual but it actually means plus or minus. From the federal perspective, an automaker can release a car that reads 50 mph when it's actually going 53 mph and it would be federally legal. Though I'm sure that would open up the automaker to lawsuits over speedometer accuracy. Thus, many automakers tune their speedometers to run faster than actual.
Many automakers like GM, Toyota, and Ford will all read dead on. My 1997 International 3800 also reads dead on at any speed. Of course, that runs the risk of your speedometer running slow should you upgrade to taller tires.
I've also asked some engineers about this and the consensus is that while the speedometer will read fast, the odometer should be actual.Fun fact: Federal law says speedometers must be accurate within +/- 5 mph of actual at 50 mph. Most people misquote the law as meaning you can't design a speedometer that runs more than 5 mph faster than actual but it actually means plus or minus. From the federal perspective, an automaker can release a car that reads 50 mph when it's actually going 53 mph and it would be federally legal. Though I'm sure that would open up the automaker to lawsuits over speedometer accuracy. Thus, many automakers tune their speedometers to run faster than actual.
Many automakers like GM, Toyota, and Ford will all read dead on. My 1997 International 3800 also reads dead on at any speed. Of course, that runs the risk of your speedometer running slow should you upgrade to taller tires.
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Interesting!It's normal, all smarts do it to some degree!
Fun fact: Federal law says speedometers must be accurate within +/- 5 mph of actual at 50 mph. Most people misquote the law as meaning you can't design a speedometer that runs more than 5 mph faster than actual but it actually means plus or minus. From the federal perspective, an automaker can release a car that reads 50 mph when it's actually going 53 mph and it would be federally legal. Though I'm sure that would open up the automaker to lawsuits over speedometer accuracy. Thus, many automakers tune their speedometers to run faster than actual.
Many automakers like GM, Toyota, and Ford will all read dead on. My 1997 International 3800 also reads dead on at any speed. Of course, that runs the risk of your speedometer running slow should you upgrade to taller tires.
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The speedo, aren’t that far off.I'm a LOT more aware of it now since I got a ticket for going 93 in a 70 last month!
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The speedometers in both of our 451 smart cars read about 3 mph faster then the speed indicated on the Ultragauges that are in both cars.
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If it bothers you that much, the speedometer needle can be removed, moved slightly counter-clockwise and reinstalled. The trick is to make sure the needle is in the correct position at 0 before reinstalling. It may take a few attempts to align it correctly. I had to take mine apart because of an LED backlight issue.
If you put bigger tires on your car that will do it
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I'm running 185/65R15s front and 205/60R15s rear, and speedometer seems accurate when compared to GPS readings. Tires are 25.5 and 24.7 inches in diameter. About as close as I could get with different front and rear combo.
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