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The condition of your car can have a HUGE impact on fuel mileage. Take care of your car, and you can get its full potential fuel mileage. Neglect it, and it can quickly lose efficiency or leave you stranded.

Where To Get Maintenance Info

There’s no way I can teach you everything about car maintenance in this course, but I can give you some basic pointers and resources that you can use to learn everything you need to know.

The first place I’d recommend looking is in your car’s owner’s manual. If you have one on hand, read it. If not, purchase one from the dealer or Amazon, or just download a copy. Sure, they’re loaded with obvious things every driver knows, but there are also valuable tips that are specific to your car. They usually give you a maintenance schedule, basic maintenance instructions, and much more. Read through the manual and do what it says.

Next, I’d recommend seeing if you have maintenance records for your vehicle. If so, make sure your car isn’t due for anything. If you aren’t sure, it’s a good idea to perform basic maintenance ASAP and start keeping a log so you’ll know when it’s due again.

If you’re a do-it-yourselfer (or want to be one), be sure to pick up the Chilton or Haynes manual for your car. It will give you step-by-step illustrated instructions for nearly every maintenance or repair task your car might need performed. They usually also have a section for people new to car work, and if that’s you, I’d recommend reading those chapters.

Whether you’re a DIY person or not, I’d recommend joining an internet forum and Facebook groups for your model of car. On Google, just type in “(name of your car) forums” to get started. On Facebook, just type the make and model of your car in the search box on top. There are hundreds or thousands of enthusiasts ready to help you with nearly any question.

Basic Maintenance Tips

Here are a few basic tips to follow while you keep all of the information you get from the above sources in mind:

Intake and Exhaust (for gas/diesel motors)

Make sure your car’s air filter is clean. A dirty filter can seriously impact your gas mileage by making the engine work harder to breathe in. Stock filters are under $20, so if you aren’t sure when it was last replaced, go buy one.

If your car’s exhaust is leaking, damaged, rusted out, bent or crushed, your car is going to have trouble breathing out. Get your exhaust fixed to get the mileage restored. If your car’s catalytic converter is plugged up or old, having a muffler shop replace it with a high flow model can make big differences.


Make sure these fluids and lubricants are getting changed according to schedule: (items with a * might not apply to electric vehicles)

  • Oil*
  • Transmission fluid*
  • Coolant
  • Differential fluid (might be part of transmission fluid)*
  • Power Steering Fluid (if applicable)
  • Windshield washer fluid

Be sure to check these fluids regularly, especially the oil and transmission fluid.


Be sure to regularly (every oil change for gas/diesel, every other month for electric, at least) check all engine belts, coolant hoses, and any other rubber parts under the hood. If they’re looking worn or cracked up, change them ASAP. These parts could leave you stranded if they break.

The “Check Engine” Light – Trouble Codes

If your car’s “check engine” light comes on (or is already on), be sure to get it checked out. When this happens, your engine’s computer has detected a fault and is storing a code to tell you what’s wrong. You can go to most auto parts stores to get this code checked for free, so there’s no excuse for driving around with it on and not at least knowing why. You can also buy a low cost bluetooth dongle for your car’s diagnostic port and get the codes on your phone with an app like Torque.

Many check engine codes are related to engine sensors and emissions components, and with this fault you might be getting much worse mileage than you could be getting.

Once, I had an 80’s car with a faulty EGR solenoid code. Most enthusiasts wouldn’t fix this problem because you could get AutoZone to clear the code right before the test to pass, but I didn’t have time to deal with a failed test so I replaced the part just in case. With the issue fixed and the EGR system working properly, I gained 5 miles per gallon on the highway. The part was $160, and the gas saved was around $150 per year at the time. Plus, the emissions were among the cleanest the testers had seen for a car of that year.

Another time, my SUV started showing a code, and gas mileage suddenly got terrible. The code said my car needed a $20 thermostat to warm up properly, and I changed it myself, saving hundreds of dollars a year on gas.

The point of these stories is this: if you have a code, get it checked. Not checking it can be costing you BIG at the pump.

Be Observant and Proactive

If your car does anything unusual, makes different noises than usual, puts off smoke, or gives you any other cause for concern, FIGURE IT OUT. Don’t assume it’ll be OK. Don’t say “next week” for several weeks in a row. Ask a friend. Ask a mechannic. Ask people online. Google it.

Whatever you do, DO SOMETHING. It might be nothing, and it might be able to wait. But find out right away.


Tires are, quite literally, where the rubber meets the road. They can have an enormous impact on your mileage if they’re low and can cause a nasty wreck if they overheat and blow out. Be sure to take special care of them.

If you are going to read nothing else from this section, read this: Many tire shops (especially Discount Tire in my part of the country) offer free tire checks. Go once a month and they’ll check the air pressure in all four tires, and inspect them for you. You might not even have to get out of your car.

Visual Checks

Every time you get in the car, take a quick look at your tires. If they look normal, you’re probably OK. If they look flat, bulgy, or otherwise unusual, check the pressure and/or get them inspected at a tire shop.

Weird Handling

If your car seems to be “splashy” or “bouncy” when going down the road, stop off and take a quick look at the tires to see if they’re low or otherwise troubled. If you’re still unsure, use a tire gauge to double check.

Proper Pressure

At the very minimum, your tires should be inflated to the pressure listed on the car’s sticker. This sticker is usually mounted on the inside of the door jamb. You might also be able to find the information in the manual.

This minimum pressure is set by the manufacturer for a balance of several factors. On the one hand, most drivers want a quiet, squishy, comfortable ride where they don’t feel the jolts and bumps. Manufacturers respond to this by recommending somewhat low, but usually still safe, tire pressures.

On the other hand, higher pressures are a trade off. You might get get slightly better mileage. You also might get better handling and grip in some situations, but worse handling and grip in others. Your braking might not be as effective, leading to longer stopping distances. You’ll most likely get a harsher ride and more road noise.

You’ll find opinions from a variety of credible sources recommending manufacturer pressure, slight increases, and big increases. Whatever you choose to do, I don’t recommend exceeding the maximum pressure listed on the side of the tire. You might get a blowout. Some drivers exceed this number by a few pounds and do OK, but doing this is not guaranteed to be safe by the tire manufacturer.

Auto Body

Your car’s body panels can also have a big impact on gas mileage. Around town, this will probably not make a big difference, but on the highway, it becomes a bigger deal the faster you’re going.

If your car has broken, loose, or cracked panels, you are probably losing out big on the freeway. Get the part(s) fixed or replaced to get those MPGs back. At the very least, tape the big cracks up with smooth tape to keep the air from flowing the wrong way at speed.

Make sure your car is free from debris (mud, leaves, dust piles, pine needles, etc). These little obstructions can change the air flow at freeway speeds in unpredictable and bad ways, costing you at the pump.

Finally, fix up any big dents or gouges in the body. These can interrupt air flow and create “low pressure” zones that suck your car backward at speed. You’ll keep moving forward, but these zones will be making your car work harder to get through the air than it should.

Aerodynamic upgrades is a topic I’ll be addressing in a later chapter in more depth, but for now just be sure your car is doing as good as it was from the factory.

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