GPS speed reading...
 

Would somebody know how accurate is it?
I know there is a delay in reading but if travelling in constant speed the GPS reads about 7mph slower then the cars speedo.

Thanks

The GPS will be more accurate than the car. My car reads a constant 3-4 mph quicker compared to GPS measurements. I think the cars speedo's have a margin of safety built into them in Europe.

so what about the speed on cameras? Could I go by the speed on the GPS or rather stick with the speedo on the dashbord ???