Five Sneaky Ways to Save Money on Gas:

Gas has gone up more than 40 cents in the last month, and according to Triple-A, the national average now sits at $3.54 a gallon. You probably know that having enough air in your tires is important, because it can improve your gas mileage by about 3%. But here are five more sneaky ways to save money on gas.

#1.) Buy Gas at Night or Early in the Morning. Gas stations store their gas underground, and it's denser when the ground is cold. So you actually get slightly more gas for your money if you pump before the sun comes up.

#2.) Try to Hit the Pump Midweek. Gas prices tend to rise slightly on Thursday, then drop back down on Tuesday or Wednesday.

#3.) Don't Get Gas Until You Need To. It's heavy, so driving with a full tank burns more fuel. But don't drive around on fumes either . . . it can screw up your fuel pump.

#4.) Don't Use High-Octane Gas If You Don't Need It. It seems obvious, but apparently some people still think high-octane gas is good for their low-octane cars. So just to be clear, unless you're driving a high-performance car, a motorcycle, a truck, or an SUV, the higher octane level won't improve your car's performance, and it's a waste of money.

#5.) Don't Drive Aggressively. According to the Department of Energy, 60 miles per hour is the most fuel-efficient speed on the highway for most cars. And according to a recent article on MSNBC.com, speeding can cost the equivalent of between 21 and 71 cents per gallon.