Is it true that one shouldn't generally let a car run below a quarter tank of gas?

gasoline, gas tanks
Dear Tom and Ray:

I've heard from many different sources that it is unhealthy for a car to be low
on gas often. Allegedly, it puts wear and tear on the engine if you always let
it get to "empty" before refilling the tank. What's the story here? I'm dying to
know if I should be visiting the gas station more often. -- Matt

TOM: Well, you probably should be visiting the gas pumps more often, Matt. It's
not a big deal, but there are two pretty good reasons for filling up the tank
when you get down to about a quarter full.

RAY: One is that on most cars, the electric fuel pump sits at the bottom of the
gas tank. And the gasoline actually serves as the pump's coolant. So if you
drive around with the needle on "E," you're allowing the fuel pump to run hotter
than it should, and potentially shortening its life.

TOM: But the more important reason for not driving around on "E" is so you don't
run out of gas. Think about it, Matt. One three-mile hike back down the highway
with a gas can in your hand is going to take more time than all of the extra
gas-station stops you'll make combined if you fill up a bit sooner.

RAY: And last time I checked, the breakdown lanes didn't have vending machines,
complimentary restrooms or those nice covered awnings for when it's raining.
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gasoline, gas tanks

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