Ask a Question

What's more accurate - a speedo or a satnav?

The speed recorded on my satnav is 3mph slower than the speedometer reading, which is likely to be accurate?

Asked on by

The satnav shows your GPS speed across the surface of the planet triangulated by at least three satellites. So if you are on a flat, straight road, the speed it shows will be your true speed. Your speedometer will be out.
Tags: speedometer
Similar questions
Cars made before 1932 do not have to have a speedometer. Are there any special dispensations for these cars when they pass through camera controlled average speed sections of road? GPS speedos have issues...
How accurate are car speedometers and what is the effect on accuracy of changing running radius of tyre as tyres wear?
I sold a 10 year old car with 27,000 miles and a full service history, only to be told a week later that the car had a speedo change eight years ago and has actually covered 35,000 miles. The dealer that...
 

Ask Honest John

Value my car