rrtex1

Why does the speedometer show 3-4 miles faster than actual speed of car? Hooked up to computer to show speed compared to GPS compared to speedometer, first two are the same and speedo shows 3 mph faster.

jllphan

rrtex1

One thing I find odd is the car's computer shows 3-4 mph less than what it displays on the speedo

DBJoe996

I know mine is 4 MPH off...if I drive 34 MPH by the speedometer the road side radar says I'm going 30 MPH. I've heard speculation that it is a pre-factored deal for European cars marketed in the ROW, and US. But that could also just be internet garbage. I never watch the speedometer very much really, just the tachometer and driving with the flow of traffic.

ejdoherty911

That's how we shave off some 0-60 time!

wyovino

It's intentional. Many posts about it. My other German car does the same thing. You can get the actual MPH via OBDII

European Union member states must also grant type approval to vehicles meeting similar EU standards. The ones covering speedometers[7]
[8]
[9] are similar to the UNECE regulation in that they specify that:

• The indicated speed must never be less than the actual speed, i.e. it should not be possible to inadvertently speed because of an incorrect speedometer reading.

Splitting Atoms

Until a couple of weeks ago, I assumed my Mazda3 did the same thing. For years I have been driving 12 or 13 over on the highway, assuming I was going about 9 over. I found out that the Mazda3 speedometer is dead on.

RSBro

Mine is consistently 4 mph under, my Lexus is consistently 2 mph under.

mattie_k

If you are looking at the speedo while driving, you're going too slow.

dan_189

My speedo is out by 4kmh when im doing 100kmh so i'm actually doing 96kmh for those that use kmp/h

shootermcgavin

noticed mine was showing a solid 4mph higher than actual speed, glad to know i'm not the only one?

Southern Man

indymcsc

So strange. Mine is 4mph faster than my actual speed too. Is there any way to make it accurate?

DBJoe996

Smaller wheel diameter. The speed is derived from the speed sensors in the wheel hubs, and it is all digital. So a smaller diameter wheel would spin faster. However, I don't think any one would go for that.

indymcsc

So I checked and I'm running the correct tire specs that came with the car. I thought a smaller diameter would spin faster