Years ago, there was a prototype electrical generator shown on TV -
possibly Tomorrow's World etc.

It was a low ramp on which one wheel of a vehicle was driven and parked.
In the ramp was a pair of rollers driving a generator. The other vehicle
wheels were chocked. With the car in gear and at tickover speeds a
useful amount of power was generated.
I seem to recall the demonstration was a farmer going out to repair a
gateway and being able to run an electric drill to assist the repair.

Does anyone know if this was ever taken to a commercial product and have
any references to it?

I have an application where something like this would be a possible
solution.

Thanks in Advance

Bob