13 Steps to Maximize MPG of Your 5.7 HEMI Vehicle

Chrysler’s 5.7L V8 HEMI is one of the most famous four-wheel engines, known for its beast power and muscular sound. But like everything in life, it has some drawbacks: poor mileage. The 5.7L V8 produces 390 BHP and delivers 14 to 20 mpg in cities and highways. If you wanna know how you can get the maximum MPG out of your 5.7 HEMI, then be seated and keep reading. [Spoilar alert; this guide will not address commonly known practices like avoiding the use of AC or regular maintenance.]

The short and straightforward answer to how you can improve the MPG on the 5.7 HEMI engine is by regular maintenance, speed-controlled driving, and less rapid accelerating and stopping.

Let me explain in more detail, so you know what I am talking about and can take action.

13 Steps tells you how to increase MPG on your 5.7 HEMI vehicle

1. Use the right engine oil.

The type of motor oil you use in your 5.7 HEMI engine can impact fuel economy. According to some studies, using synthetic motor oil in your engine can improve fuel economy by 3.2%. This is because synthetic motor oil flows more easily at low temperatures than conventional motor oil, so the engine can run more efficiently.

engine oil for Hemi 5.7

Another logic is that low-viscosity oil offers less resistance to moving engine parts, thus improving the economy.

If you’re unsure of the type of motor oil to use in your 5.7 HEMI engine, consult the owner’s manual or ask a qualified mechanic. If your HEMI is bogging down when accelerated then you need to check this guide.

2. Check and replace your air filter.

car air filter

A clean air filter is vital for two reasons when it comes to fuel economy. First, it allows the engine to breathe more easily, improving efficiency. Second, a clean air filter means the engine doesn’t have to work as hard to suck in air, which also helps improve fuel economy.

For best results, check your air filter every 12,000 miles (19,000 km) or so and replace it if it’s dirty.

3. Upgrade to cold air intakes – costly


A cold air intake is an engine air intake system designed to bring cooler air into the engine. This helps improve the engine’s efficiency and makes it more powerful. In terms of fuel economy, a cold air intake can improve mileage by up to 2%. 

A cold air intake is an excellent option if you’re looking for a way to get better fuel economy and more power from your 5.7 HEMI engine. Here are the proven cold air intake systems for your 5.7 HEMI engine.

4. Keep the underhood clean – easy

One of the best ways to improve fuel economy is to keep the underhood clean. This includes the engine bay, the radiator, and the intercooler. A clean engine bay helps improve airflow and keeps the engine running cooler, leading to better fuel economy.

keep the underhood clean

Similarly, a clean radiator intercooler helps improve airflow and keeps the engine from overheating, leading to better fuel economy.

In short, keeping the underhood clean is a great way to improve fuel economy.

5. Use cruise control whenever possible – easy

Another popular way to improve your MPG is to use cruise control whenever possible. By keeping your speed consistent, you can avoid wasting gas by accelerating and then braking frequently.

cruise control whenever possible

When you accelerate quickly, you use more fuel than if you were to accelerate at a steadier pace. This is because your engine has to work harder to get up to speed, which uses more gas. So next time, take it easy on the accelerator and avoid sudden stops. You’ll save fuel in the long run, and your wallet will thank you.

6. Avoid carrying unnecessary weight.

According to ItstillRuns, “Every 250lbs of extra weight costs you a loss of 1mpg”. So, if you carry the extra weight in your car that you don’t need, leave it in the garage. Not only will this improve your fuel economy, but it will also make your car handle better and make it easier to stop.

So next time, try not to carry any unnecessary weight in your vehicle.

7. Keep your tires inflated to the proper PSI – most effective

maintain proper tire pressure for better mpg

One of the easiest and most effective ways to improve MPG is to keep your tires inflated. You probably know this, but I can’t stress this enough cause, surprisingly, many drivers don’t take it seriously.

When your tires are properly inflated, they have less rolling resistance, so your engine doesn’t have to work as hard to move the car. This can lead to a significant improvement in fuel economy.

Check the tire pressure to ensure they are properly inflated with a tire pressure gauge. You can find these at most auto parts stores.

If you want to go above and beyond, use low-rolling resistance tires. These tires are designed to reduce rolling resistance, leading to better MPG.

8. Install performance chip

When you drive a 5.7 HEMI vehicle, you want to do everything possible to improve your gas mileage. One less known way is the use of a performance chip also sometimes referred to as a tuner.

Performance chips work with engine computers. The chip optimizes the gas-to-air ratio in the combustion mix, leading to better gas mileage. In addition, performance chips can also provide other benefits, such as increased power and torque.

9. Use engine e-Fan

An electric radiator fan can help improve your vehicle’s fuel efficiency, especially when driving on the highway. The fan helps to cool the engine, so it does not have to work as hard to maintain its operating temperature. This can lead to a significant reduction in fuel consumption. In addition, the fan can also help to reduce engine wear, which can improve engine health and further enhance your vehicle’s MPG.

10. Keep windows close

As with properly inflated tires, the aim is to keep drag and resistance as little as possible so the engine can work with as little stress.

At higher speeds, open windows increase air resistance, making your vehicle heavy for that moment, which translates to more weight for the engine to work on. So whenever possible, keep windows closed.

For vehicles with a 5.7L HEMI engine, it’s recommended that you use 89 octane gasoline. This will provide you with max performance, increased MPG, and reduced carbon emission. Using premium gas is not gonna help with efficiency.

12. Try a fuel additive – not sure of the effectiveness

While not as popular and also as effective for MPG improvement, a fuel additive is something you can give a try if you are desperate for the economy.

13. Regular tune-ups

car tune up

And finally, the tune-up. Keep up with regular tune-ups to ensure your 5.7 HEMI vehicle is running as efficiently as possible. This means taking your vehicle for service according to the manufacturer’s suggested schedule. During a tune-up, your mechanic will check and adjust various systems and components, including the ignition, fuel injection, and emissions controls.

Tune-ups help to keep your car running smoothly and can improve fuel economy by up to 4%.

Over to you!

The list of vehicles featuring 5.7L is long. It includes Chrysler 300C, Jeep® Grand Cherokee, Dodge Durango, Ram pickup trucks, and Dodge Challenger R/T and Charger R/T models. And when I am talking about improving MPG on 5.7 HEMI, I am talking about all these vehicles.

So, by following the tips mentioned above, I am sure you will significantly improve your vehicle’s MPG. This will not only save you money at the pump, but it will also help to reduce your carbon footprint. So don’t wait; start implementing these tips today and see how much you can improve your fuel economy. You can also refer to my performance upgrade guide to get the juice of max power and economy from your HEMI.

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