Has anyone else noticed this, when i'm doing 30mph through those digital speed checkers at the side of the road it says i'm doing 25/26mph and always have angry drivers behind me so I have to do around 34/35 on the speedo, i've been driving a demo car for a week now and it is doing the same so I know it's not mine!

Over reading speedo is normal, but it's not usually that much out.

I'd suggest checking it with a GPS device while doing a constant speed.

They are allowed to over read by 10%, but not under read.

That way if you brake the law you know you are.

Mine is about 4% over.

The roadside digital speed displays are also not that accurate, and display a higher speed than reality to slow you down. If you have a GPS speed display, and drive through at 30mph the roadside displays usually say something completely different.

Over reading speedo is normal, but it's not usually that much out.

I'd suggest checking it with a GPS device while doing a constant speed.

They are allowed to over read by 10%, but not under read.

That way if you brake the law you know you are.

Mine is about 4% over.

i can understand 4% or 10 but this seems more

The roadside digital speed displays are also not that accurate, and display a higher speed than reality to slow you down. If you have a GPS speed display, and drive through at 30mph the roadside displays usually say something completely different.

its showing a much slower speed, wish i had a sat nav that told me my speed! the PID is only a basic navigon :(

My Yeti also reads a different speed to the Tom Tom, 75mph on the speedo is 70mph on the TomTom, however a weird phenomenon I have noticed is the oddometer reads different to the trip. The main mileage recoding part is ok but the trip loses a 1/10th per thousand miles, if you set the trip as your car turns an exact figure like 20,000 when you watch the trip change at 21, 22, 23k etc the trip is a couple of tenths behind, my Audi also did this

I thought you can set the PID in sat nav mode to indicate your actual speed? You can with some Garmin's and Tom Tom's.

Just had a look at my Navigon PID. The setting is Navigation, page 1, last item - 'show altitude and speed'. The factory setting is off (no).

The European regulation, ECE-R 39, is more concise, stating essentially that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70). Never low.

Most skodas read 5mph high.

PID reads correct speed.

My Yeti also reads a different speed to the Tom Tom, 75mph on the speedo is 70mph on the TomTom, however a weird phenomenon I have noticed is the oddometer reads different to the trip. The main mileage recoding part is ok but the trip loses a 1/10th per thousand miles, if you set the trip as your car turns an exact figure like 20,000 when you watch the trip change at 21, 22, 23k etc the trip is a couple of tenths behind, my Audi also did this

Our Yeti on 16" 215/60 rims/tyres is very close to the Garmin given speed; about 2mph above thought out most of the national speed range.

TP