If you're worried that your car is going to run out of gas before you get to the gas station, what's the best way to drive to get the most out of the last drops of gas?

The thing that uses the most gas is rapid acceleration, so you want to avoid that and drive at a constant, low speed (obviously coasting as much as you can), trying to break as little as possible). This week's Sierra Club Radio episode has an interview with the guy who holds the title of "best-mileage driver in the world"...he can get 100 mpg out of a Prius by using his gas-saving techniques. He is a bit wacky but he does also include some really good tips for the average driver who wants to squeeze the last drops of gas out of their tanks. you can listen online at http://www.sierraclubradio.com

the interview with the "Hypermileage" guy, Wayne Gerdes, is about 15 min in, I think.

Driving a Prius for maximum efficiency isn't quite the same as driving a regular car. Generally, you're getting your best gas mileage just after you switch into your highest gear. To save gas, accelerate as little as possible, and stop as little as possible. Brake as little as possible. If you're on the highway, slow down to 55 if possible.

All that advice is for a regular car. Those Prius guys are amazing, though--but they have some strange braking pattern they use to max out the engine's storage of electricy...

And stay out of the left lane on the freeway

A friend had told me to switch into neutral when going downhill when I was out of gas and in the middle of nowhere. Would that mess up my transmission?

shifting into neutral in an automatic or standard shift car will not hurt the transmission, BUT caution when shifting back into the Drive gear (auto) or high gear (manual) that you get it into the correct gear position. you also must take your foot off the gas so you do not overrev the engine, thus using more gas. Also, drive at the slowest safe speed will dramatically increase that mileage.

turn off the a/c

38mph is the most efficient mileage for a car. my calculus professor actually worked out the whole problem.