If you’re old enough to remember the early 70s, you’ll recall that one of the ways that the Japanese car makers were successful was bringing in cheap cars that were very fuel-efficient. They did quite well doing that, and if there were 100 MPG cars (or even 50 MPG cars) to be developed at competitive prices with the features that people want, you could be sure somebody would build them. Honda and Toyota are certainly putting enough effort into hybrids that they would do something else if it were easy to do.

Overall mileage potential is mostly a function of vehicle weight and aerodynamics, with a bit of engine design thrown in. In around-town driving, the aero factor isn’t terribly relevant, so it depends more on how much weight you have to get moving, and how much gas you burn during idle. For freeway (non rush-hour), it’s mostly about the size and aerodynamics of the car.

Gas engines are somewhere around 25% efficient, and there’s not a lot of ability to improve them, given the basic constraints of heat engines. Turbines are more efficient because of their higher temperatures but don’t lend themselves well to vehicle applications.

You might want to read:

http://www.straightdope.com/classics/a3_150.html

Continuing the subject of energy conservation, congress should read my last post, but instead they have other ideas. Currently daylight savings time is the first Sunday in A […]