Most of them are, but 10 years ago a fellow gave me a 1991 Yugo which I converted to electric power. I removed the engine and all the parts connected to it. I made my own adapter plate and put an 8 HP DC motor in it. With a controller and 6 12volt deep cycle Gell batteries, I drove it 13,000 miles @ 5 miles at a time back and forth to work. When the price of gas went back down, I put it in my shop and stopped using it as the batteries were about shot. I could get it up to 55 mph during each short trip and recharge it over the lunch hour. To keep warm in the winter time, I plugged in an oil heater before leaving work or home.
Now that gas is over $5.10 in my town, I am thinking of putting lithium batteries in and running it again. It was fun to drive and not have to stop at a gas station. Converted it weighted less than the gas powered model.