Sat Nav systems

[Gladeian]

My sat-nav shows the current speed of my vehicle - how accurate can I expect this reading to be?

[Grandpappy]

A lot MORE accurate than speed cameras and speed guns used by the mob. Most speedos on cars are about 2-3% out (fast). The so called 10% idea doesn't apply,it's a myth-that's why they don't write eg: 30+-10 %. Your sat-nav is a very sophisticated piece of equipement.

[Gladeian]

Thanks - does the accuracy depend on the quality/cost of the sat nav itself or are we only talking a very small possible deviation depending on quality of the unit?