Many eons ago, cars used carburetors to deliver fuel. In order to more power, better fuel economy (and better emissions), engines were switched to fuel injection. Even Porsche bowed to the inevitable and switched to water cooled engines, as the air cooled engines couldn't meet emissions with the power Porsche wanted.

Later yet, computers, and feed back loops from Oxygen sensors were added in, to better control the fuel.

So the answer is, there continue to be ways to improve fuel economy outside, of what you've covered.

For example an engine will run more efficiently, if it doesn't have to run through a range of RPMS (ask a diesel owner). One way this can be addressed is with a technique similar to what new cruise ships use. A hybrid gas/electric vehicle, were the drive train is COMPLETELY electric, but the engine, is simply an electric generator running at a constant speed.

On Tuesday, November 01, 2005, at 07:41AM, John Rodgers <inua@CHARTER.NET> wrote:

>
>What else???
>
>Is it really possible to get more BTU's from a pound of fuel than a
>pound of fuel has??  What good does better mixture control and
>vaporization actually do? Given better mixture control and vaporization,
>can fuel efficiency actually be increased beyond where it is now, just
>on that basis?
>