The Institute of Advanced Motorists is urging drivers not to be over-reliant on their satnavs.
Satnavs are a major cause of driver distraction, the organisation says.
Drivers are putting their lives at risk by operating them while on the move, or by blindly following instructions and not anticipating the road ahead.
IAM chief examiner Peter Rodger said: “Satnavs should aid navigation and safety by helping drivers to make decisions early.
“They should not distract you from the road. At 70 miles an hour you will travel the length of a football pitch in the three seconds it takes to press a satnav button.”
The IAM recommends that drivers:
l Practice driving with the satnav on while ignoring the display. You should be able to use just its voice directions without taking your eyes off the road. If you’re not careful, a satnav display will draw your attention from road conditions and traffic. Use the display only to confirm the instruction. This only needs a glance.
l What you see takes priority over what the satnav says. We’ve all heard the stories of people being stuck in narrow lanes, driving into rivers and being directed into oncoming traffic. If the road looks wrong, don’t take it.
l Operate the satnav only when you’re parked. Even if it’s a one-touch satnav, operating it draws too much attention from the road.
l Always check the route before you set off. Some satnavs have a habit of occasionally picking unsuitable routes and won’t know the latest road closures or the restrictions on the vehicle you are driving. Always take a map as back up.
l Don’t rely on safety features such as rest-break information. You should be able to drive safely without these. Take your rest-breaks when you feel tired or at least every two hours.
l If you are about to miss a turn, don’t attempt a dangerous manoeuvre to comply with the instruction. The satnav will always recalculate a new route, so drive on until it does. If you need to turn or change direction make sure it is safe and legal to do so.
l If you are using a mobile phone satnav app, don’t use it hand-held while driving.
l Mount your satnav properly where you can see it without moving your head but where it doesn’t interfere with your view. Make sure it isn’t in the airbag’s way and that the power leads do not interfere with the car’s controls.
l Don’t use satnvas as a speedometer as they can be inaccurate.