Speedo Accuracy

[320CDI]

How accurate is the speedo.

I set my cruise control at 70 mph and the car shows approx 68 on the aveage speed on the computer (I reset it when I am traveling at this speed) - the speedo shows 70.

I set my maximum speed warning tone to x and the speedo always goes about 3 MPH over the figure.

My car is standard from BMW - no change to the wheel size which I guess would effect these kind of things??

Do BMW build in a bit of protection for their customers against speed camera's?

This might explain why I have seen posts on this site saying that the cars are actually faster than the BMW spec - maybe they are not and its just the speedo that over reads.

I have to say I expected better from a quality car.

Anyone else see this?

[EnvyM3]

Originally posted by 320CDI@Sep 1 2004, 01:50 AM
How accurate is the speedon.

I set my cruise control at 70 mph and the car shows approx 68 on the aveage speed on the computer (I reset it when I am traveling at this speed) - the speedo shows 70.

I set my maximum speed warning tone to x and the speedo always goes about 3 MPH over the figure.

My car is standard from BMW - no change to the wheel size which I guess would effect these kind of things??

Do BMW build in a bit of protection for their customers against speed camera's?

This might explain why I have seen posts on this site saying that the cars are actually faster than the BMW spec - maybe they are not and its just the speedo that over reads.

I have to say I expected better from a quality car.

Anyone else see this?

Nope! According to the last ticket I got, I was clocked at 85mph and that how fast I was going. So it seems pretty accurate to me.

[320CDI]

so does your speedo and your avearge mph computer match (i.e set your cruise control at 70mph on the motor way and then reset your av MPH computer and see what it says)

[doughboyea]

Ticket at 90mph, doing exactly that, Police dude used a laser gun, accurate within 1-3mph....i think.

Dough

[320CDI]

ok but same question what does the computer say you are doing?

[EnvyM3]

Originally posted by 320CDI@Sep 1 2004, 03:02 PM
so does your speedo and your avearge mph computer match (i.e set your cruise control at 70mph on the motor way and then reset your av MPH computer and see what it says)

No, my computer is all f-d up because my outside temp gague is shot. Haven't had a chance to fix it yet. But I will let you know once I get it fixed

[KillFox]

I will go try it out and post back later.

[chris323i]

I think in general, the cruise control does not keep your car at exactly the speed you set all the time. My car (on cruise control) speeds up on uphills and slows downhill.

[320CDI]

try it just for a short distance on a flat road - it will change on hills etc but over a short flat distance it should be acurate! (imo)

[KillFox]

Worked perfect for me on cruise control. 60.3 avg speed , doing 60.

[320CDI]

Must just be my car then - I wonder if it is because of the wheels they put on the sport model?

Although I am sure that my old car did it as well - not sure if the wheels were bigger than standard on that one??

[Greenbean]

Don't automobile makers program an amount of inaccuracy into their speedometers? I spent 4-years with Acura/Honda and they all have a 1%-10% inaccuracy limit...So as to error on the slower side of the speed your guage indicates...My Acura is actually 1-3 MPH slower than my guage displays.

[320CDI]

That's what I am wondering - and if they do it explaines why some people who have posted feel that their car is faster than the bmw spec sheets say.

Cheers