Accuracy of speedo

[Sheilz]

Has anyone with an r55 checked the accuracy of their speedos? I've been checking Dougall against my RA and to be honest not sure if its the RA that's playing up or if my findings of a greater discrepency between th two at higher speeds than lower have been noticed by anyone else. Specy's digital read out was always two miles exactly behind the RA but am finding that with Dougall its reading as being between 3 and 5 miles out. RA's been lying about these past few weeks, its getting on a bit too so not sure if it can be trusted anymore. Not too keen to test it agaist a speed camera!

[illegalhunter]

Speedos are usally +10% to stop you getting done by the spped cameras. This also means you clock up 10% more miles you didnt do. Check your spped with a sat nav, there very accurate

[The Dogfather]

The inaccuracy of the speedo varies between 7% - 3% depending on the wheels fitted, and the speed you are travelling at. Running on the standard 17" size my speedo over-reads by 7% at 70 mph, but on the 18"s with 225/40s its actually bang on.

The 16"s should over read by about 3%, will confirm that when the winter wheels go on...

[baptie]

found difference of 6 miles out with the Tom Tom, how accurate are they?

will look at my speedo vrs digy speedo the day, getting dragged to ikea!!!

[Sheilz]

This also means you clock up 10% more miles you didnt do. Check your spped with a sat nav, there very accurate

How does that work? Is it something to do with how the car's gears etc are set up?

[Stewart]

Did about 1000 miles there down to Yorkshire and around and back up the road, just over 500 miles with the Tom-Tom on and it usually told me I was a few miles/hr lower than the digital on the car. I’m on 16s. Varying speed with long spells sitting around 70MPH.

How accurate is those slow down signs that read your speed, pass one all the time and it smiles and says 28mph when the Speedo says 32 ish.

[Sheilz]

Those signs are always on a par with my road angel but not with speedo. Stil haven't got used to the variation in variation between the two.
Did you enjoy your run to Yorkshire? I did a round trip to Nottingham the week before. Was well pleased with Dougall and though it pains me to say it, was a more comfortable drive over the distance than its ever been with specy. Amazing, never thought it would be possible to improve on perfection

[Stewart]

Loved it, only a week but took in the east coast Scarborough, Filey and Whitby, Sandsend down to Flamborough Head etc. Again thanks Val for the parking space at Sandsend in place of your Cooper S if your out there.

Came back over the Buttertubbs, but what a road to get there, think it’s the most twisty,tight road I’ve been on per square mile down the bottom of a Dale Valley.

Got 52 Mpg over all. Some of the roads across the Moors are first class but even for me too much traffic to really enjoy. Makes you appreciate what we had up Sutherland with nae traffic

[Forbes]

Got 52 Mpg over all.

You should hold your head in shame!