The Laser Speed idea is said by CBBC to be "a clever device which could save lives on our roads."
It "will help slow cars down to the recommended speed limit by using special satellite technology. When the car reaches the speed limit, Charlie's voice comes out of a box by the steering wheel and tells the driver they need to slow down."
The result of the online poll will be broadcast on That's Genius! on CBBC One on 17th December.
Click here to vote
Interestingly, such a device already exists. Sort of. It was displayed at this year's Interbike and was invented by the father of two under-12 year old boys. However, rather than being GPS driven, the device used a radio wave detector to warn of the proximity of radio-beacon equipped bicycles.
The device only works if the motorist buys the detector and cyclists have the beacons fitted, a not-very-likely scenerio. However, when BikeBiz.com put this point to the inventor he said: "Yes, but the owner of the first fax machine was also out on his own. When the second fax owner bought their machine, the technology was seen to work. It needs a change in thinking, innovative products need time to work."