How to Make an Old Car More Fuel Efficient: 30 Ways

BMW E34 old car blue near a wall with graffiti

Are you tired of constantly pulling into the gas station? Unless you convert your classic car into an electric vehicle (which might not be worth it), then you’ll be doomed to keep doing that. However, you can change how often you have to fuel up.

The short answer is that you want to combat the things that are hurting your fuel efficiency. Driving inefficiently, using the wrong gas or oil, hurting your car’s aerodynamics, and neglecting a fuel leak will hurt your mileage. The quickest way to boost your fuel efficiency is to roll up the windows, turn off the AC, strip unnecessary weight, and drive smoother with plenty of coasting and cruise control.

You might not be able to teach an old dog new tricks, but you can certainly teach your old car how to have better fuel efficiency. In this guide, I’ll review 30 different ways to improve fuel efficiency for your old car. Most of the examples are simple to implement and will provide immediate results.

What Is Fuel Efficiency

The term “fuel efficiency” refers to how well your car can convert gasoline into miles behind you. It’s given in units of miles per gallon (mpg), which refers to how many miles you can go from a single gallon of gas.

A car that achieves 40 mpg will drive 40 miles on a single gallon of gas.

German old man driving a VW volkswagen car very fast on the highway of Stuttgart Autobahn

Keys to Higher Fuel Efficiency

While it might not seem like it, there are actually ways to unlock higher fuel efficiencies without major changes to your car. You might not be surprised since the title of this article is “How to make an old car more fuel-efficient”.

Your fuel efficiency revolves around a few key factors:

  • How the car is driven. Perhaps the biggest category revolves around how you physically drive your car. Slamming on the brakes and gas is a quick way to ruin your fuel efficiency.
  • The aerodynamics of your vehicle. Aerodynamics is a measure of how well your car slices through incoming air. Boxy vehicles have worse aerodynamics, so more fuel is wasted just trying to fight the air as you drive.
  • The vehicle’s weight. Carrying 1,000 pounds is a lot harder than carrying 10 pounds. Your car is going to burn more fuel if the vehicle weighs more.
  • The mechanical performance of your vehicle. The engine and ancillary pieces of equipment will determine how efficiently fuel is being used. Engines that are designed with fuel efficiency in mind will have more favorable mpg’s than ones that focus on performance. An old Camry offers 30mpg while a modern F1 car gets about 3mpg.
  • Where the fuel is being used. Running accessories that take a lot of power will steal fuel efficiency away from your engine.
  • Whether or not there are fuel leaks. You can kiss your fuel efficiency goodbye if you have any kind of fuel leak. Any gas that spills on the road before you get to use it is wasted.

Why Old Cars Suffer More

A big reason why fuel efficiency is worse on old cars is that it wasn’t a big focus. Today, we have groups like the EPA who demand that car manufacturers achieve certain miles per gallon on their new cars.

Opel classic cars meet up parked near a cliff old cars retro

Back then, cars were just about performance, styling, and comfortability at affordable pricing.

In addition, technology has come a long way. We have a ton of added sensors that can help optimize your fuel efficiency. We also have more fuel-efficient engines that we’re dropping in cars today.

Since your car came out before this was possible, it’s really hard to make the changes. Luckily, there are some options for you.

30 Ways to Make an Old Car More Fuel Efficient

Now it’s time to talk about the good stuff. Here are 30 major ways to improve your old car’s fuel efficiency. Try them out and see how much your mpg boosts by.

1. Tune Up Your Engine

Replacing your spark plugs, oxygen sensor, air filter, and fuel filter is what goes into an engine tune-up. Simply doing these will immediately boost your fuel efficiency.

For old cars, your oxygen sensor is going to be somewhere in the exhaust system.

Spark plugs should be changed out every 30,000 miles, for reference.

2. Stick to Higher Gears at Speed

Your engine will have better fuel efficiency at lower revs. Due to this fact, it’s always best to stick to higher gears when you’re cruising down the highway.

Vintage 4-speed manual trasnmission interior of a car
Retro 4-speed manual transmission shifter

When you shift up, your engine settles to a lower rpm value. Rather than driving in fourth gear at highway speeds, consider shifting up to fifth.

However, older vehicles may only have 3-speedo or 4-speed transmission so there might not be much you can do the older your car is. You will lose the acceleration and performance that you have in fourth, but you’ll unlock better mpg’s.

3. Regularly Check Your Tires

Tires are a huge deal on your car. They are the only interface that your car has with the road underneath you.

They are also largely responsible for your miles per gallon. If your tires are underinflated, overinflated, don’t have enough tread, or have too much tread, then you’re losing out on fuel efficiency.

This is why checking the health of your tires regularly is such a big deal. You’ll want to check the tire pressure, thread health, and see if there are any surface defects on your tires.

4. Clean Your Battery

If your battery is corroded, your alternator might need to work too hard. If this is the case, then you’re simply wasting fuel just trying to keep your battery juiced up.

Old car old battery cable corrosion on one of the terminal posts

It’s a good idea to regularly pop the hood and inspect the battery. Ensure the terminals are rust-free, there is no liquid on the top of the battery, and the connection is firm.

5. Cruise Control Is Your Friend

Cruise control can save you a ton of gas. It takes the guesswork out of maintaining your speed — a process that can lead to overcorrection and a waste of fuel.

Hitting the gas too hard wastes fuel, and that can easily happen when you’re trying to maintain your speed on the highway.

Even when cruise control is activated, make sure your foot is hovering over the pedals in case you need to make a quick decision. Too many drivers get complacent and keep their driving foot far away from the pedals. This just adds a delay to your reaction time which might cause you to get into an accident.

6. Make Sure You Don’t Remove the Gas Pump Prematurely

There’s also a strange place where people hurt their fuel efficiency: the gas pump.

I’ve seen a lot of drivers keep the pump lever held in as they remove the pump from their car. Gas pouring onto the ground, and you get charged for it.

Man pumping gas into the gas fuel tank of the car

If you’re calculating your gas mileage based on how much gas gets pumped into your car, you just ruined the calculation. Even doing this for a few seconds can completely screw up your math.

If you live in a state where you pump your own gas, make sure you release the pump lever before removing the nozzle from your car.

7. Avoid Idling

They say that idle hands are the devil’s tools, but did you know that an idling car is the mpg’s worst enemy?

Idling is when your engine is running but your car is just sitting there in park mode. Typically you’ll idle your car to warm it up when you’re waiting for somebody, or while you check your phone before leaving the parking lot.

Car dash instrument cluster speedometer tachometer revving idling with backlights illuminated in the dark

You should never idle for more than a minute. This is just a pure waste of fuel and a quick way to ruin your fuel efficiency.

It doesn’t take more than 30 seconds for the fluids to fully pump in your vehicle. In addition, the quickest way to warm up your car in the morning is to start driving it. Your engine needs a load on it to truly warm up, hence why idling is so inefficient in this department.

Another thing that idling does is drain your battery slowly. The alternator can’t charge as fast as it wants to.

The quick answer? Don’t idle.

8. Shred the Un-needed Weight

Stripping weight from your car is a quick way to boost your fuel efficiency and give your car better performance.

At the same time, it’s a quick way to make your ride less comfortable and seat fewer people. This is because the seats in your car are surprisingly heavy, and that’s one of the first things that people look at when they want to reduce their car’s weight.

Other options are to take out unnecessary components, ditch the spare tire, and take out the HVAC system.

This should only be the option for people who want to make their old car more fuel-efficient by any means necessary.

9. Ditch the Rooftop Cargo Carrier

If you have a rooftop cargo carrier on your old car, it’s got to go. It hurts your fuel efficiency in two ways:

  • It adds unnecessary weight
  • It ruins your vehicle’s aerodynamics
Old car with a roof rack cargo carrier with suitcases

By detaching and removing it, you just boosted your efficiency. If you really need to use it, consider only attaching it during your trip.

The best option is to find another place to store your things instead of using the cargo carrier at all. After removing the back seat in an effort to remove weight, now you have a huge compartment to store things. Win-win.

10. Make Sure You’re Using the Right Gas

It’s also worth mentioning that you need to use the right gas in your car. If you thought that all gas was the same, you’re in for a treat.

Different gas options offer different levels of octane. This is used to boost performance and fuel efficiency in vehicles. Some older engines especially ’80s and older run better on ethanol-free fuel which prevents premature deterioration.

However, premium gas won’t give you any benefits unless your car specifically calls for premium gas. Simply pumping in more expensive gas doesn’t make your car become a Porsche, after all.

11. Optimize Your Route

Before starting your car, you should map out your route. Sticking to an optimized path will always optimize your fuel consumption.

VW volkwagen mini-van miniature with a map on a desk planning a trip in the USA

This might mean jumbling up the order that you run your groceries in. Google Maps has a great feature where you can add all the stops in a single trip and shuffle them around to find the most optimized path.

Getting in the habit of doing this will permanently boost your fuel efficiency and will probably save you time on the road, too.

12. Use the Right Oil

In addition to using the right gas, you also need to use the right oil. This can have an enormous impact on your fuel efficiency.

For reference, oil is used to lubricate your engine. A well-lubricated engine will perform at its peak. Using the wrong oil will immediately hurt your fuel efficiency.

If you change your own oil then pay special attention to the oil you buy off the shelf. 10W-20 and 10W-30 are very different options.

13. Practice Smooth Acceleration, Smooth Braking

It’s also a good idea to adjust how you drive. Opting for smooth acceleration and braking will optimize the fuel that you use.

A person pressing on the accelerator gas pedal of a car

Of course, you’ll need to aggressively apply the brakes in the case of an emergency.

When you’re not in an emergency situation, you should practice applying either pedal very gradually and smoothly. It also makes for a more enjoyable ride for your passengers.

14. Minimize HVAC Usage

Your car’s HVAC is one of the largest energy users in the whole vehicle. If you blast the AC, you’ll feel a noticeable difference in your performance. You’ll also notice a steep decline in your fuel efficiency if you keep it blasting for long enough.

Part of why NASCAR drivers get so sweaty is because they don’t have HVAC in their vehicles. They just have a little fan that sucks in air and blows it on them.

15. Keep Your Windows Up

In addition to turning off the AC, you’ll also want to keep your windows up. As wind enters your windows, it slows down your car.

It’s all a matter of aerodynamics. You want all the wind to effortlessly glide over your car like it isn’t even there. With your windows down, the wind funnels into your car and it becomes a miniature parachute.

Rolling up the car windows through the car window control switch

This makes your car use more fuel to keep going, ruining your fuel efficiency.

The best practice is to keep your windows all the way up and your AC completely off. This isn’t viable for people who live in Florida or Arizona, but it’s just a suggestion.

16. Use Your Automatic Engine Start-Stop

Some cars have a cool feature where the engine will automatically stop when the vehicle comes to a complete stop, like at a red light.

As I mentioned earlier, idling your car is a quick way to waste fuel. By turning off the engine completely, you don’t have to worry about idling at red lights or stop signs.

There’s a good chance that your older car doesn’t have this feature unless it was a cutting-edge vehicle back in the day. The solution? Become your own automatic engine start-stop. One downside is the wear-n-tear on the starter so use with caution.

When you come to a stop, turn off your car and restart it when you’re ready to move again. If you’re just learning how to drive a manual, you can pretend that this is what you’re doing next time you stall at a stop sign.

17. Avoid Speeding

As tempting as speeding is, it can really hurt your fuel efficiency. In addition, it’s a pretty unsafe thing to do behind the wheel.

There’s no rush to get to work or practice. Plus, speeding probably isn’t going to make up the time that you need to make up.

Old VW Volkswagen Golf blue hatchback going fast speeding on the road

An independent study suggested that going 80 mph uses 25% more fuel than going 70 mph. That’s pretty significant.

An episode of MythBusters showed that 45 mph was the magic number. By staying under this value, you can make a ton of enemies on the highway while optimizing your fuel efficiency. I would never suggest that you do that, but it’s a good idea to stop speeding.

18. Coast to Stops and Downhill

Coasting isn’t a great thing to do in work or school, but it’s a best practice behind the wheel if you want to optimize your fuel efficiency.

Coasting is when you take your foot off the brake and gas and simply let physics do its thing. With a long enough, flat road, your car will eventually come to a complete stop under its own power from coasting.

I like to coast on downhill roads and whenever I see a stop in the distance. It’s a nice way to preserve some fuel and it’s more comfortable. I still apply the brakes closer to the stop, but there’s a generous portion of the road where I don’t do anything but steer.

19. Change Your Oil Regularly

Picking the right oil is important, but it’s critical that you change your oil regularly. As I explained in this guide, your oil should be changed per the manufacturer’s suggestions. There are three types of oils that have three corresponding mileage and time values.

Close up of a person filling up topping off car engine motor oil during an oil change

In general, you’ll need to change it at least once a year. If you’re using conventional oil, you’ll change it every 5,000 to 7,500 miles which could occur multiple times each year.

Fresh oil has the best lubricious properties that your engine needs. By lubricating the whole engine, you’re getting the most out of it. Yes, that also means the most fuel-efficient engine possible.

20. Revving Your Engine Isn’t as Cool as You Think

When I was younger and dumber, I thought that a revving engine was the coolest noise possible. I can still admit that it’s a great sound, but it’s also irresponsible.

For one, it can hurt your car’s transmission if you do it while your car is moving.

More importantly, it simply wastes fuel. Revving your engine is when your engine goes through all the motions without hooking up the transmission to the engine. In other words, your engine gets all revved up with nowhere to go since power doesn’t get transferred to the wheels.

This is done by either having the car in “Neutral” or “Park” while you press the gas pedal. It’s a bad idea.

21. Lower Your Suspension

Another way to boost your aerodynamics is to drop the height of your car. You want to be as low to the ground as possible if you’re trying to optimize your aerodynamics.

Mercedes-Benz 560 SEC AMG chrome wheels old car lowered suspension close-up
Mercedes-Benz 560 SEC – Lowered Suspension

As a reminder, a more aerodynamic car wastes less fuel which means your ride is more fuel-efficient.

Also, it’s a great way to make your car look cooler. I love a dropped car, regardless of the make or model.

22. Keep Your Foot Off the Brake Unless You’re Applying it

Some drivers use both feet to drive an automatic vehicle. They’ll keep their left foot on the brake pedal and the right one on the accelerator.

Don’t do this. Ever. The biggest reason is that it’s easy to get confused when you’re making a split-second decision and accidentally slam the wrong pedal.

In the case of fuel efficiency, you could be fighting against yourself. Even if you’re lightly applying the brake unknowingly with your left foot, you’re killing your fuel efficiency.

23. Dirt Roads are Evil

As much as I love driving down dirt roads out in the country, they wreak havoc on your miles per gallon. In the quest for optimized fuel efficiency, dirt roads are evil.

Car on a dirt road passing through rural lowlands

Your car uses a lot more power to navigate across the surface. Since it’s not flat and grippy, your tires have to work overtime. As you can probably guess, this extra work equates to extra fuel wasted.

24. Keep it All Aligned

Tire alignment will also help with your engine’s performance. Misaligned tires will be fighting each other as you drive down the road. Even slight misalignment can result in a dramatically different mpg for your car.

Have a mechanic check out the alignment and balance of your tires before getting back on the open road.

25. Pick the Right Tires

Speaking of tires, are you using the right ones? Off-roading tires with deep treads might look cool, but they’re highly inefficient on the highway.

You’re just using extra grip and weight on a road that doesn’t need it. Unless you’re an avid off-roader and you don’t know when your next adventure will be, you should keep those massive tires in the garage.

Opt for all-season tires to get the most out of your fuel efficiency.

26. Replace Your Old Gas Cap

Interestingly enough, your gas cap might be why your car’s fuel efficiency is hurting. A gas cap will keep vapors in your tank so they can burn off without escaping.

Car fuel tank filler cap with the fuel door open and the other side of the gas cap visible

If the seal is damaged or deteriorating due to age, your gas cap might be allowing those precious vapors to escape.

Buy a new cap and replace the old one then check to see how your fuel efficiency changes.

27. Add Some Aero

There are little body kits you can throw on your vehicle to boost the aerodynamics of your car. Things like diffusers and covers can help you glide through the air.

This is good news since the air is always slowing you down, ruining your miles per gallon.

28. Maybe Your Engine/ Transmission Need to Be Rebuilt

In extreme cases, you might be looking at a full engine or transmission rebuild. This can get super expensive and time-consuming, but it might be the only option for certain cars.

This is where components are removed, cleaned, or swapped out, then reinstalled into your engine or transmission.

Mechanic using a torque dynamometer wrench to install the engine cylinder head on an old engine of a car

This becomes more common as cars get older. If you choose new components, then you’ll modernize your engine and should see a big boost in performance and fuel efficiency.

If you’re facing this problem, you might also need to consider if it’s worth repairing your vehicle or not.

29. Perform Routine Maintenance Routinely

Routine maintenance has the word “routine” in there for a reason. You want to make sure you’re not neglecting this preventative maintenance, especially for older cars.

Even though an old Chevy might feel bulletproof, you’ll need to do all the little things like rotate the tires, replace the oil, and replace all the filters.

Failure to do so will make your engine start to underperform, ruining your fuel efficiency.

It’s also the best thing to do if you plan on your old car getting even older. Routine maintenance is a great way to make cars last longer.

30. Let a Mechanic Check Out Your Engine

Every once in a while, it’s a good idea to get a mechanic involved. They have expertise that people like us simply don’t have.

Taking your car to an honest mechanic can help your fuel efficiency. How? They might be able to spot a leak or inefficiency.

Mechanic rebuilding an old car engine with the piston and valves visible in a garage on a towel

From there, they’ll know how to fix the problem and get your miles per gallon back up to where it should be.

If you’re skeptical, you can always do the repairs on your own. At the very least, you should get an inspection and diagnosis from a mechanic since they have the tools and experience that your car needs.

Conclusion

There are plenty of ways to make your old car more fuel-efficient. I just covered 30 of my personal favorite ways. If you want to read more car guides, check out the rest of my site. In addition, feel free to peruse a list of car products that I love.

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Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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