5mph difference from actual mph

[nootrak4]

I purchased a Ultra Gauge to help monitor my car and RPM readings. After having it for over 2 weeks or so i thought the UG was broken because it had a MPH lag, but it turns out to be the Smart Car which as the Lag.

After 10 MPH the Cars MPH Gauge starts to mark more MPH then the car is actually traveling. After it reaches 50MPH it has a 5MPH over the actual speed of the vehicle. At first I thought this was a problem with my Ultra gauge, but then I used a GPS tracker that can track how fast you are traveling and the reading was the same as the Ultra Gauge, So I enlisted a buddy to go 60 on other car and put the car on Cruse control and I followed and at 60 MPH the cars MPH Gauge reads 65MPH when the car is actually is travelings slower at 60MPH. This is not as bad as if it was the other way around, but this is still a problem.

Anyone else has this problem. If you would like to test this look for GPS Speed Tracker on the Android Market and you will see for your self.

This goes up as you speed up, When you reach 10MPH (car MPG) you are actually going 9MPH by the time you reach 20 you are actually traveling at 18mph and so on until you reach 50mph (car MPG) which means you are really traveling at 45mph and then it a 5mpg Lag.

If someone wrote something about this I'm sorry i looked and didn't see anything.

Here is a Video
Video

[NCC1701]

5 MPH is a bit more than most people see. The difference I observe, and others seem to note too, is more like 3 MPH. I'm sure it varies a bit. And, it's not unique to smarts. Most cars I'm aware of read higher than actual speed.

Best explanation seems to be that auto manufacturers would rather err on the side of caution. Since speedometers have some variation, better to read high than to read low.


Here's my car, showing GPS reading 68 MPH, while the speedometer reads about 70 MPH. Meanwhile, Scangauge reads 67 MPH (lower right figure on gauge).

[nootrak4]

Originally Posted by NCC1701

5 MPH is a bit more than most people see. The difference I observe, and others seem to note too, is more like 3 MPH. I'm sure it varies a bit. And, it's not unique to smarts. Most cars I'm aware of read higher than actual speed.

Best explanation seems to be that auto manufacturers would rather err on the side of caution. Since speedometers have some variation, better to read high than to read low.


Here's my car, showing GPS reading 68 MPH, while the speedometer reads about 70 MPH. Scangauge faily well agrees with GPS.

I was expecting a Lag between GPS and the Car speed Maybe by 1-2mph but this is really unacceptable and the UG is plugged right into the cars computer.

I tested the car to see what is the Top Speed and i was able to reach 95mph, until i got scared and was surprise that i was able to pass 90mph which the car is suppose to be limited to 90 by the computer

I tested this on my Optima SX Turbo and on A Ford Escape, because i started to read up on this and it very accurate on my other cars. What does your little Meter say that is next to the other gauges. I was looking into it but settled on the UG.

[NCC1701]

Originally Posted by nootrak4

I tested the car to see what is the Top Speed and i was able to reach 95mph, until i got scared and was surprise that i was able to pass 90mph which the car is suppose to be limited to 90 by the computer

My GPS has recorded a little over 91 MPH. I often hear 90 MPH cited as the electronically imposed limit. But, I've read somewhere that the limit is actually 92.

What does your little Meter say that is next to the other gauges. I was looking into it but settled on the UG.

You were probably typing while I was editing my post. The Scangauge reads 67 MPH, while the GPS reads 68, and the speedometer looks like 70 or a little over.

[Brabus007]

Its kind of funny, because the car knows how fast its going... Speed limited to 90 MPH but the Speedo says 95... Its a joke that this much error has not been fixed after 4 years...???

[SmartDigger]

my gps and scangage are exactly the same ...my speedo is 3 off I set my CC on 75 and I know I an going 72. not a big deal to me.

[rfernatt]

Originally Posted by SmartDigger

my gps and scangage are exactly the same ...my speedo is 3 off I set my CC on 75 and I know I an going 72. not a big deal to me.

It was the same for me with stock tires. With 195/50s, it's closer to 2 MPH off. All of my vehicles are always 2-3 MPH off at 65-70 MPH on the speedo vs GPS vs radar signs vs SG.

[CorkyF]

Mines also about 5mph higher.....at least when I'm over 55, its pretty accurate to about 30-40mph. My Suzuki scooter was even worse, till I added a little gadget called "the speedo-healer", now its 100% accurate. Wish they made one for the Smart.

[nootrak4]

Originally Posted by rfernatt

It was the same for me with stock tires. With 195/50s, it's closer to 2 MPH off. All of my vehicles are always 2-3 MPH off at 65-70 MPH on the speedo vs GPS vs radar signs vs SG.

I don't get it, I don't get this one my other cars it a 2012 Kia Optima SX Turbo and a Ford Escape XLT 2005 and when i hooked up the UG they read the same as the MPG Gauge.

This things reminds me of the BS HP that ever Manufacture claims, when in reality there cars do like 10-20% less then the advertised HP.

[jwight]

I would take the car back or trade it in for a car with a really accurate speedometer.