A well-tuned car and driving at constant speeds both save gas, but some of the tips you've heard, like getting more gas by filling up when it's cool outside simply aren't true.
Jeff Bartlett at Consumer Reports has compiled a list of myths about fuel efficiency, and he quickly debunks that one.
"Temperature has very little impact on the amount of fuel going into your car because the gasoline is stored underground where the temperature really doesn't change throughout the day," he explains.
The one about getting better mileage from better-known gas stations is also a myth.
"No-name gas stations are getting the fuel from the same places as the big name companies. It's all gasoline and your car's happy to burn it no matter where it comes from," Bartlett says.
Maintaining proper tire pressure helps slightly.
Bartlett says that's more of a safety issue.
And those additives claiming to be able to stretch a gallon...
"The EPA, likewise, has tested about a hundred different products through the years and it has not, yet, found one that will work," Bartlett says.
Other experts say the ultimate way to save gas is to downsize the type car you drive.