When you really stop and think about this question, you realize how obvious the answer is. Or is the answer really all that obvious? You see there’s this lovely rating for vehicles that just so happens to be one of the most popular buying considerations for consumers looking for a new ride.

Of course, we’re referring to the MPG (miles per gallon) rating that vehicles will be rated with. As most of you are fully aware, MPG is the distance that a vehicle can travel per gallon of fuel, and it’s measured in miles. Do you see where we are starting to get at here?

How many miles in a gallon of gas? Seeing how the average car sold in the United States has an MPG rating of around 25, most drivers will get 20 to 30 miles on one gallon of gas. That’s it then, right? Just look at your vehicle’s MPG rating and you’ll know EXACTLY how many miles you’ll be able to get on one gallon of gas.

Oh, if it was only that easy. The reality is even though a car’s MPG rating is a very good measurement of fuel economy, there are a plethora of additional factors that can affect it. This makes figuring out how many miles in a gallon of gas a lot more complex.

Due to the numerous outside factors, it’s almost impossible for any one driver to figure out the exact number. Basing it off of your vehicle’s MPG rating is an excellent start, but you’re also going to want to take into consideration the abundance of outside factors to get a clearer understanding of what can truly make a difference regarding your ride’s fuel economy.

What factors impact the MPG rating(s) of your car?

Photo by Ambitious Creative Co. - Rick Barrett / Unsplash

If you’re familiar with vehicles and shopping for them, you more than likely know that you’ll see more than one MPG rating for a vehicle. City, highway, and combined are the three major categories that are rated by the EPA.

City driving is characterized by driving conditions that include traffic jams, frequent red lights and stop signs, and frequent stop-and-go situations (in general). This will typically be the lowest rating due to the constant starting, stopping, and idling of the vehicle.

Highway driving is characterized by traveling for longer distances without frequent stops on roads that accommodate higher speeds. This will generally be the highest rating. Then, finally, combined driving is merely a combination of both highway and city driving (as you’d expect).

That’s really just scratching the surface right there because when you want to get the most accurate answer to the question of how many miles in a gallon of gas, you also have to start factoring in the following:

  • Ensuring your tires are properly inflated
  • Change your oil regularly
  • How aggressively you drive
  • The electrical accessories being run
  • The terrain you’re driving on
  • What you’re hauling or towing
  • What the weather’s like (yes, that’s a factor!)

Don’t worry, we’re going to dive much further into those factors listed above. And let’s do that right now, shall we?

The importance of proper tire pressure

It’s safe to say that most people probably wouldn’t think of their vehicle’s tire pressure when thinking of what’s possibly affecting their fuel economy. While the importance of ensuring proper tire pressure goes beyond fuel economy, it certainly can play a role here.

In addition to decreasing traction, poorly inflated tires will increase the number of times that they have to rotate to move the same amount of distance. Check your tire pressure often to ensure that the PSI is at the recommended level set forth by the manufacturer.

Be sure to change your oil regularly

As with the tire pressure of all four tires on your car, regularly changing the oil in your vehicle isn’t ONLY important for increased fuel economy. If you skip routine oil changes, the engine oil in your car can become dirty and reduce its functionality.

This can cause major issues such as excess friction between the engine’s many components, thus wearing them down a lot quicker. Rusting and overheating of the engine can also result, as well as higher fuel consumption. The last part is what’s relevant to this post, but we wanted to briefly point out the other problems of not changing the oil regularly.

Now, due to improved oil and fuel technologies in more modern vehicles, it’s not uncommon for vehicles to now only need an oil change once every 7.000 to 10.000 miles. An older vehicle may require an oil change every 3.000 miles, however.

Don’t forget about your RV, either! That’s going to require an oil change, as well, but how long does an oil change take on an RV? Just a little food for thought. Anyway, back to business.

How aggressive are you as a driver?

No, this question has nothing to do with passing a driver’s test or your safety (and the safety of others). We’re certainly not downplaying the importance of driving safely but having a bad habit of aggressive driving (that good old lead foot) is arguably the factor that affects fuel economy the most.

And when attempting to figure out how many miles in a gallon of gas, you need to assess your own driving habits. Now, when it comes to aggressive driving, there are three things that come to the forefront.

Driving too fast is the most obvious of the three (as aerodynamic drag increases when you travel at higher speeds) but accelerating too quickly also plays a role. Finally, stopping too suddenly can be problematic, which is common if you drive too fast as you’ll often catch up to cars on the road quicker than you should.

Accelerate slowly (not too slow to become a hazard on the road), drive with the speed of traffic, and stop soon enough to ensure you don’t need to slam on your brakes. In fact, a natural and brakeless deceleration can help to increase fuel efficiency.

It’s not crazy for aggressive driving to lower your fuel economy by up to 30 percent at highway speeds and up to 40 percent in city traffic. So, in short, stop being such a crazy, psychotic, madman driver, would ya?!

Other factors that impact the MPG

When it comes down to it, it’s crazy how many small factors can affect the answer to the question of how many miles in a gallon of gas. Outside of the three we just discussed, here are some other driving considerations to keep in mind.

Electrical accessories: Yep, running certain electrical accessories can decrease fuel economy. The most common culprit is the AC in your car. Running the AC on max can reduce your vehicle’s MPG by 5 to 25 percent as compared to not running it. Sometimes, the weather’s just too darn hot to warrant not running it. But just don’t max it out on full blast the whole time.

Hilly terrain: It’s important to note that when the EPA tests fuel economy, they assume vehicles operate on flat ground. So, if you’re driving on mountainous or hilly terrain or even just on unpaved roads, your fuel economy can suffer as a result.

Using four-wheel drive: Vehicles that have four-wheel drive are tested in 2-wheel drive when figuring out MPG. As such, using 4-wheel drive will lessen your fuel economy. Engaging all four wheels will make the engine work a lot harder.

Cargo and towing: If your vehicle is loaded up with cargo, the additional weight can decrease your fuel economy. If you’re hauling cargo racks on the top of your vehicle with items on top, this can increase aerodynamic drag and hence lower your MPG. Finally, if you’re towing a trailer possibly with the Honda Odyssey or the Toyota 4Runner, expect the fuel economy to drop (sometimes drastically).

Frequent cold weather and short trips: The engine in your car operates efficiently when it’s warmed up. Therefore, if you’re constantly taking short trips (especially during the cold-weather months) your car isn’t going to be running at the desired temperature. This lack of efficiency can lower your fuel economy.

Is it bad to drive your vehicle close to an empty tank of gas?

Photo by Erik Mclean / Unsplash

The reason we bring this question up is that when you talk about “how many miles in a gallon of gas,” it makes you wonder if it’s addressing the possibility of running out of gas and needing to know how many miles one would have left to get to a gas station.

Nowadays, vehicles will often provide an estimated miles remaining feature of some sort to indicate how many miles the vehicle has left with the fuel inside the tank. However, the above factors can affect that. Anyway, this thought leads to the question of whether or not it’s bad to drive your vehicle close to empty.

We’ve more than likely all done it before (and some of us probably do so more than we should) and doing so can have a negative impact on your vehicle. In addition to possibly damaging your catalytic converter, doing so can damage your fuel pump as debris that settles at the bottom of the tank will be sent through the fuel pump with a tank that’s nearly empty.

Final thoughts

We sure could’ve made this easier by saying the following. How many miles in a gallon of gas? Just look at your vehicle’s MPG and you’ll have your answer. We wouldn’t be lying by saying that, but we surely wouldn’t have told the entire story.

The reality is there are too many outside factors to provide a definitive answer to this question. Our advice is to keep all those factors in mind, keep up with your vehicle maintenance, and don’t drive like a reckless fool!