How to save money on gas

With gas running about $3 a gallon we are still paying more than a dollar less than most other countries (except our neighbors to the north and south.) However, saving money is never a bad thing.

Ok the most under rated way to save money on gas is to check the inflation of your tires, under inflation can cost you >7% of your fuel efficiency, plus tires aren’t free and wear faster when under inflated. You can find the proper inflation on the VIN sticker on the driver side door frame. On long, high speed trips slight over inflation can improve your mileage, but since it can affect ride characteristics and traction on snow or mud I mention it only for completeness.

Remove excess weight, since every 100 lbs of extra weight is a ~5% reduction in fuel efficiency, so the 400 lbs of crap in your truck causing you to have 20% worse gas mileage.

If you are going over 45 mph and your car is less than 20 years old then running the AC is more efficient than open windows. Sure the compressor loads the engine, but over 45 the aerodynamics of the car are comprised more by the drag of open windows, than the load. Below 45 it is a wash, but I like to be cool.

If you drive a truck cover the bed or remove the tailgate. Remember a solid tail gate has the same aerodynamic properties of a wall and kills your mileage.

If you will be idling for more than a minute turn off the engine, a hot fuel injected engine uses no more gas to start than it does any other time. A minute is just a guideline, but long waits at a drive through window or creeping traffic kill your mileage, so go in and get the food, or wait till traffic decreases you will save lots (like a third or more). It pains me to say this but driving slower helps too, newish cars are most fuel efficient between 45-60 MPH. Above 70 you take a substantial hit in fuel economy, and going 80 requires almost twice the fuel of 55, so how fast do you really need to get there?

Do your maintenance a clogged air filter, EGR valve or crack case vent, kill the gas mileage, as does a worn out oxygen sensor, dirty fuel system, or just bad tuning. Get you car a checkup and replace some cheap parts, you might save >50%. Remember $8 for a new air filter can mean 15% better mileage alone. If your car is newish then get it washed and waxed, the dirt and bugs can cost you up to 2% fuel efficiency. (Why do you think you never see dirty UPS or FedEx trucks?)

The number one way to save money on gas is buy the right fuel for your car. Premium or super is not better gas, is simply can be compressed more before it explodes. In fact 91 octane gas contains lots less energy than 87 regular gas. Is super a good deal? Well 91 costs like a quarter more a gallon and you have to burn up to 10% more to make the same power, so I am going with no! Now if you drive a modern luxury car or have super/turbo charging than you have a high compression engine and need 91 to prevent knock, for the rest of us 87 is fine. 89 or midgrade is a total waste of money since it is too high octane for regular compression engines to make good power but too little for high compression engine to prevent knocking.

While I am on the subject most fuel additives are a waste too. If you buy good quality gas (like Exxon or Chevron) instead of Racetrac’s water/fuel mix and are least once a week going more than 15 miles in one trip at high speed, you fuel systems and valves are plenty clean. The detergent in good gas isn’t really detergent it is solvents and ions but for marketing detergent = cleaning and is easy for most people to understand. However, it really does clean the fuel system, but only if the engine gets hot and stays hot. Now if you are buying cheap gas or only make short trips, some injector cleaner can help but you still have to make that long high speed trip for it to work. Don’t be fooled jet fuel is just kerosene not some magic super fuel, Teflon/PTFE just burns and kills the Cat, remember there is no magical mystical fuel additive on the market that can improve MPG. More importantly there is no gadget that can improve your MPG, that doesn’t involve at least removing the valve cover or altering the computer, so beware of snake oil vendors. (For the love of gd never add water, ATF or oil to your fuel, unless you drive a WWII era fighter plane, ask me and I can explain.)

If you really want to save money buy a diesel since diesel engines are by their very nature >25% more fuel efficient than gasoline engines, and because they are massively overbuilt can last three as long as a gas engine. If that isn’t an option cut back on your mileage, plan you errands and actives so you drive the minimum number of miles, or at least never backtrack. Or if you can instead of driving, bike or walk. In my case once it cools off I will walk the 4 miles to the store and back, it is good exercise and at current prices saves me 50 cents.