Speedos - how accurate are they?

[oblio]

The post sums it up really. When it reads, say, 60mph, what speed is/could the car be actually going?

Mine is a 56 plate DB9 Volnte btw...

ta

[GlynMo]

I believe that, legally, a speedo can be up to 10% out so, at an indicated 60, you could be doing anywhere between 54 and 66. I've never checked the V8V speedo but I have an aftermarket satnav in my Subaru which shows speed and the Subaru speedo reads about 8% high. I suspect all car speedos (argggghh, not the swimming thingies!) read high if they're not spot on, but that's mere supposition.

[:J:]

Get something with GPS and check it out

[GingerWizard]

At 50 my car is actually doing 47, at 100 its 93. Which is why mine goes off the clock (160) when its doing its factory 147mph....

does not really help as i drive a Type R Civic and your rolling around in a aston... (honestly i'm not jelous)


N.b actally had the car up to 155.7mph which had the needle back at its start point......

[Al 450]

It can only legally read up to +10% -0% so in other words it can't show you going slower than you really are. VH car speedos are very accurate but obviously it depends on tyre wear and temperature / inflation as this will affect the rolling radius.

[oblio]

Cheers all

...kind of important if one were to go through a speed check camera then

[Vantagefan]

The digital speedo has a slight lag on the traditional version beside it. Something to bear in mind when slowing down for a camera....

[sadlerj]

At 70mph on my the speedo of my V8V, on a flat road the GPS says I am doing 67, it is not very far out, better than some other cars I have had.

[brianjone5]

Tyre choice (size) and tyre pressure will affect your actual speed. Best to calibrate your car and wheels with a gps that provides real-time speed. My DB7 is consistent with my TomTom, +/- 1 or 2 mph at higher speeds.