General Inaccurate spedo

[Garteio]

Been running my car for a while now and I think the spedo may be inaccurate.

Did a journey on a dual carriage way today, drove at 70 for a good bit. According to my sat nav my speed never went above 67.5mph.

Is this normal in an older car?

 

[fingers99]

It's normal for all cars -- speedos are required by law to under-read.

 

[blu73]

:yeahthat: to be honest thats really accurate for a mk1 speedo at 70mph, i tend to find they are generally over 5mph out at that speed, nearly 10mph on alot of them.

 

[Most Easterly Pandas]

It's normal for all cars -- speedos are required by law to under-read.

:yeahthat: although its actually a requirement for them to OVER read and not under read

 

[fingers99]

:yeahthat: although its actually a requirement for them to OVER read and not under read

That's what I meant -- the speed you are really, really going at should be lower than the speed on the speedo!

 

[blu73]

my black cinq that i recently sold was terrible accuracy anything over town speeds.. You could get an indicated 100mph on the clocks and barely be breaking the speed limit on the motorway lol.. But yeah they all over read a bit, the '09 alfa 159 i had was much closer to the actual speed given by GPS (which also isn't 100% accurate i would point out) but it was always reading slightly more than GPS

 

[dumbledore]

I find my punto mk1 speedo quite accurate (not much less then 1mph off at 70mph). But this may have something to do with the fact I have 14' wheels which came as standard with slightly larger tyre diameter then the usual 13' wheel.

 

[Garteio]

Thanks for all the replies, guess it means I will have to go some to get a ticket.

Good to know if I zone out and go a little above 70 I'm sill going to be doing 70 ish

 

[fingers99]

In 70 zones I'm usually cruising at 85!