Hi Allan
distance / range I think would be the deciding factor between petrol or electric powered.
I came across these whilst considering trying to copy the track system which is simply 2 old car tyres with the sides cut off and slots cut into the tread. The build itself looks labour intensive and I would imagine that the required parts for the drive train wouldn't be cheap .
Using a golf cart motor and battery leaves you with the problem of controlling two tracks for steering (unless of course you were thinking of using the steering arrangement from the plans).Maybe using two hydrostatics out of an old dead ride on would be a simpler cost effective option. As aussietrev mentioned above all other parts look to be readily available from hardware stores and engineering shops.
A hybrid system takes up a fair amount of room , is costly , but would be very handy if you ran out of fuel or had a problem with the engine whilst out and about.
Whatever option you go for ,
happy building
