Talk Morgan Forums Community Vehicle Talk (non-Morgan) Sat Nave Reiability?

I was told that the law allows for mechanical variance of the speedo of -3% and +10% so permitting your speedo to show (67)70(77).

In my experience pretty much every car I have had shows in the region of +5-10% with some Ford/Vauxhall being even worse. You could also loose a little rolling diameter from under-inflated tyres. My Phaeton shows about 2mph more than the TomTom at 70mph. My Aero shows about 6mph more than my TomTom at 70mph. Ironically I am far more likely to speed in the Phaeton due to the silence and massive torque/autobox/turbos.

In my experience the boys in blue will not look to upset your journey until you are a further 5mph over the real limit or more on the motorway. If you are showing bad road craft or near a known problem area like a school they tend to allow no variance.

I always find it fun if you look at the speed people do through roadworks or as they are passing a police car. Most police sit at 67mph on the motorway to try and reduce bunching so allowing people to make fair progress. You get piles of cars tailing the policeman and then they look at you like you are mad as you gently pass them and make off into the distance.

So if you add all of that up you could see 82 on the clock and still be safe. Then again you could be looking at a ban !