What Is MPG (Miles per Gallon)?

MPG, which stands for miles per gallon, is a measurement used to quantify the fuel efficiency of vehicles. As defined by the U.S. Environmental Protection Agency, “The MPG rating of a vehicle is the estimated number of miles traveled on a gallon of gasoline or diesel fuel consumed” (Source). Put simply, MPG measures how far a vehicle can travel on a single gallon of fuel. The higher the MPG, the more miles a vehicle can cover per gallon of gasoline or diesel consumed.

MPG is an important metric for assessing a vehicle’s fuel efficiency. A vehicle with higher MPG will be able to travel farther using the same amount of fuel as a vehicle with lower MPG. Maximizing MPG allows drivers to spend less on fuel while traveling the same distances. For this reason, MPG is a key consideration for many car buyers looking to save money on fuel costs over the lifetime of vehicle ownership.

How MPG is Calculated

MPG stands for “miles per gallon” and is the standard measurement used to calculate fuel efficiency for all vehicles. It measures how many miles a vehicle can travel on one gallon of fuel. The calculation is simple:

MPG = Miles Driven / Gallons of Fuel Used

To calculate MPG, you need to know two numbers: the number of miles driven and the number of gallons of fuel used. Here is an example calculation:

If you drove 240 miles before refueling, and you filled up with 10 gallons of gas, the MPG would be:

MPG = Miles Driven / Gallons of Fuel Used

MPG = 240 miles / 10 gallons

MPG = 24

So in this example, the car’s fuel efficiency was 24 MPG. The higher the MPG, the more fuel efficient the vehicle is. MPG gives you a standard measurement to compare the fuel efficiency of different vehicles.

Factors That Affect MPG

A vehicle’s fuel efficiency, as measured by MPG, can vary substantially depending on several key factors:

Vehicle Size and Weight

Heavier and larger vehicles require more power to accelerate and move, which burns more fuel. Large trucks and SUVs have more weight to haul around so they achieve much lower MPG ratings than smaller, lightweight cars.

Engine Size and Power

Vehicles with bigger, more powerful engines consume more fuel. Engine size is measured in liters or cubic centimeters (cc), with larger engines burning more gas with each revolution. High-performance sports cars sacrifice MPG for more horsepower under the hood.

Acceleration Habits

Aggressive acceleration and speeding will significantly reduce MPG. Rapid acceleration causes more fuel to be injected into the engine, while higher speeds increase wind resistance and drag. Gentle acceleration and cruising at moderate speeds optimize MPG.

Type of Fuel Used

Some vehicles can run on regular gasoline or higher-octane premium fuels. Since premium gas is refined more thoroughly, it produces slightly better efficiency and MPG, though at a higher cost per gallon at the pump.

Improving Your Car’s MPG

One of the easiest ways to improve your car’s fuel economy is through regular maintenance. According to Kempthorn, following the manufacturer’s recommendations for oil changes, tune-ups, air filter changes, and more can optimize performance and mileage. Proper tire inflation is also key – underinflated tires create more rolling resistance and reduce MPG. You should check your tire pressures at least monthly and before long trips.

Removing any extra weight from your vehicle can also give a boost to MPG. Take out any unnecessary items from your trunk and avoid keeping heavy items in your car when not needed. Excess weight makes the engine work harder, using more fuel.

When driving, smooth acceleration and braking helps improve fuel efficiency. Aggressive driving with rapid starts and stops lowers MPG. You can also maximize MPG by using the recommended grade of fuel – premium gas is often not needed unless specified by your owner’s manual.

MPG Ratings and Standards

In the United States, the Environmental Protection Agency (EPA) conducts fuel economy tests and assigns miles per gallon (MPG) ratings to new vehicles (Wikipedia, 2023). The EPA testing involves running vehicles on a dynamometer through city and highway drive cycles to simulate real-world conditions. Based on the test results, the EPA calculates a city and highway MPG rating which manufacturers must display on new car window stickers.

The EPA ratings provide a standardized way for consumers to compare fuel efficiency across different models. However, real-world MPG often differs from EPA estimates due to variations in driving habits and conditions. The EPA has adjusted testing procedures over time to better align with real-world results.

In addition to testing, the EPA works jointly with the National Highway Traffic Safety Administration (NHTSA) to set Corporate Average Fuel Economy (CAFE) standards (NHTSA, 2023). Introduced in 1975, CAFE standards regulate the average fuel economy across a manufacturer’s entire fleet of vehicles. The standards have increased over time, spurring automakers to improve fuel efficiency through innovations like hybrid and electric vehicles.

CAFE standards in the U.S. have historically been lower compared to fuel economy regulations in Europe, Japan, and South Korea. However, the U.S. has recently established stricter CAFE targets to reach an average of about 40 MPG for cars and trucks combined by 2026 (Wikipedia, 2023).

MPG by Vehicle Type

There are significant differences in fuel efficiency between passenger cars and trucks. On average, passenger cars achieve much higher MPG ratings than light trucks like SUVs and pickups. According to research from the Department of Energy’s National Renewable Energy Laboratory, the average MPG for passenger cars in recent years has been around 36 MPG, compared to only 26 MPG for light trucks.[1]

Hybrid and electric vehicles also tend to have substantially higher MPG compared to conventional gasoline-powered vehicles. Hybrid cars average about 50 MPG, while fully electric vehicles are rated at over 100 MPG equivalent (MPGe). This is because electric vehicles are much more energy efficient, converting over 77% of electrical energy to power at the wheels, whereas gasoline engines only convert 12-30% of energy stored in gasoline.[2]

Even within specific vehicle classes, MPG can vary widely between models. Compact sedans may range from 30-50 MPG, while hybrid SUVs achieve 25-35 MPG, significantly higher than the 15-25 MPG of conventional SUVs. Overall, choosing more efficient models within a given class can lead to substantial fuel savings over time.[3]

Fuel efficiency for new vehicles in the United States has improved dramatically over the past few decades. According to research from Transport Energy Strategies, between 1975 and 2018, the average fuel economy of new light-duty vehicles improved by 50%, from 15 miles per gallon (MPG) to 25 MPG (source). Major gains were seen in the early 1980s due to rising gas prices and new Corporate Average Fuel Economy (CAFE) standards. After staying stagnant through the 1990s and early 2000s, fuel economy rose again in the late 2000s, reaching a record high in 2014.

Experts project fuel efficiency will continue improving in the coming years due to more stringent CAFE standards passed under the Obama administration. The standards require automakers to achieve a fleet-wide average of about 41 MPG for cars and 31 MPG for trucks by 2025 (source). This represents an increase of nearly 50% from today’s levels. However, some argue the standards are too aggressive and costly for automakers. The Trump administration attempted to roll back the standards, though this move was challenged in court. For now, the standards remain in place and fuel efficiency is expected to keep rising, resulting in consumer fuel savings and reduced environmental impact.

Impact on Cost Savings

Improving your vehicle’s fuel efficiency can lead to significant cost savings, especially for drivers who log high annual mileage. The average American drives around 13,500 miles per year. With gas prices averaging around $3.50/gallon nationally as of 2022, drivers can save hundreds of dollars per year by upgrading to a more fuel efficient vehicle.

For example, improving from 15 mpg to 25 mpg can reduce annual fuel costs by about $750 if driving 13,500 miles per year. Upgrading from a 20 mpg vehicle to a 35 mpg vehicle would save around $525 annually. The more you drive and the lower your current mpg, the more dramatic the savings. Fuel efficiency improvements are one of the most effective ways drivers can save money directly at the pump.

Environmental Benefits

Improving your vehicle’s MPG rating can provide important environmental benefits. By using less fuel, you reduce overall fuel consumption. This helps conserve natural resources and reduces dependence on fossil fuels like oil. Lower fuel consumption means fewer raw materials are extracted and refined into gasoline or diesel.

Additionally, improving MPG leads to lower greenhouse gas emissions from your vehicle. Cars release emissions like carbon dioxide as they burn fuel. So the more miles you can drive per gallon, the less emissions you produce. Greenhouse gases trap heat in the atmosphere and contribute to climate change. So reducing your vehicle’s emissions helps mitigate environmental damage.

If everyone improved their MPG even slightly, the cumulative impact would be significant. Hundreds of millions of cars are on the road globally. So small changes by individual drivers can add up to large reductions in fuel use and emissions overall. Choosing a fuel efficient vehicle and driving in ways that maximize MPG benefits the environment.


As we have seen, Miles Per Gallon (MPG) measures how far you can travel on each gallon of fuel your vehicle uses. It is an important metric for determining fuel efficiency and calculating operating costs. Key factors that affect MPG include vehicle size, weight, aerodynamics, engine performance, and driving habits. There are various strategies to improve your car’s MPG, such as regular maintenance, eco-friendly driving, using the recommended octane fuel, and reducing cargo weight. Vehicle manufacturers must meet federal MPG standards and provide estimated MPG ratings to help consumers make informed choices. Fuel efficiency has gradually increased over time across vehicle types, with hybrid and electric vehicles achieving the highest MPG. Maximizing your car’s MPG translates into significant lifetime cost savings and environmental benefits by reducing fuel consumption and greenhouse gas emissions. Ultimately, being aware of your car’s MPG can help you optimize efficiency, lower expenses, and make eco-conscious choices on the road.

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