Fuel Efficiency Myths

Photo Courtesy of Wikimedia Commons.

Now that fuel prices have come back down to Earth. I’m going to talk a little bit about some common questions I get from people here at the dealership. There are lots of myths about how to save gas, and I want to try to dispel some of them.

Does filling up before your car is empty help stop with fuel evaporation?

While it’s never a good idea to run your vehicle down to the ‘E’ (because no one likes running out of gas), filling up before it gets there¬†doesn’t stop evaporation from happening. Modern cars have vapor recovery systems that stop the fumes from escaping your tank. Nowadays, just about any car you drive will trip the check engine light if your gas cap is not securely fastened or missing. You can fill up your gas tank with any level of fuel already in the tank and not notice a difference.

Does a manual get better gas mileage than an automatic?

This is a tough one to answer. A skilled driver who can control the engine with precision and times their shifting perfectly can get better mileage than an automatic transmission, yes. However, a normal, everyday driver who does not pay particular attention to those details will waste gas by shifting too late or over-revving the engine. Automatic transmissions have come a long way and are more efficient than ever, which leads to less gas wasted.

Should I fill up my gas tank when it’s cooler?

The theory behind this myth is that when a liquid is cooler, it’s denser, meaning you get more fuel for the money. Good theory, but bad practice. The gas you buy from a gas station stores their fuel underground, insulated from the elements, where there is little temperature variation. Purchasing gas in the morning, when it’s cooler will have no noticeable effect on your wallet.

Do you have any fuel myths you want dispelled?