There is a growing car hacker movement that has local inventors and tinkerers making changes to hybrid cars to improve their mileage drastically. Basically, (check that link at the beginning of this post for a good FAQ) they add the ability to plug the car in and recharge the batteries from the grid. Additional batteries are added and the car is set to run on electric only for short trips under a certain speed. Over that the gas engine kicks in. It is also available if the batteries lose their charge.

The savings come in because the car runs on electric only for local trips, the vast majority of drive time. Electric is cheaper than gas and actual gas usage drops.

This is a simplistic explanation, however it begs the question: Why don’t the car makers embrace this if it’s easy enough for an individual to build? An unholy alliance with the oil business perhaps?