There are many things to consider when buying a new car. How is the handling? What about the power and acceleration? How comfortable is it to drive? One of the most common questions is how much will it cost to run? And that’s an incredibly important question. In recent years, there have been perfectly designed, attractive, and comfortable cars that consistently received poor ratings because they are simply too expensive to use.
Most of the time, this comes down to them being “gas guzzlers,” meaning they have extremely high fuel consumption. Given the high and unpredictable price of gasoline and diesel, the energy efficiency of cars has become a key indicator to help you choose the right car for you. That’s why we have MPG and why almost every review of a vehicle will mention what its MPG is. But what is this value, can I calculate it for my existing vehicle, and how useful can it be when buying a new car?
WHAT IS MPG?
MPG stands for miles per gallon and it’s the standard unit for measuring fuel consumption in land vehicles. The figure shows the number of miles a car can travel on one gallon of fuel. For example, if your car has a fuel consumption of 50 mpg and its fuel tank holds one gallon (or 4.55 liters), you can travel 50 miles before the car runs out of fuel.
By law, every car must receive an official MPG value from the manufacturer, and this must also be made available to customers. This acts as a guide so consumers can compare energy efficiency between different models and vehicles. The EU sets the standards for British vehicles, and the tests are administered in the UK by the Vehicle Certification Agency. Because they are all standardized, they provide an accurate comparison between cars. If you’re buying a new car and looking to get something more efficient, it’s always a good idea to ask what my car’s MPG is right now and whether this car will have a better one.
HOW IS MPG CALCULATED?
The official MPG is calculated from a laboratory test on a rolling road. A single model is tested in each product range. A car is tested on two cycles: the urban cycle and the extra-urban cycle. The urban cycle test starts from a cold engine and then mimics city driving at speeds not exceeding 30 mph. This test lasts 2 and a half minutes and includes a series of stops and starts to recreate the type of driving needed in urban areas. The extra-urban test is designed to see how a car would behave outside the city and lasts 4.3 miles with a maximum speed of 70 mph. The temperature is standardized to 20-30 degrees, and there is only the driver in the car. The MPG stated by a manufacturer is then an average of the two MPG figures from these two tests.
HOW DOES THIS DIFFER IN REALITY?
Since MPG is done under hypothetical laboratory conditions, there will always be a difference between a car’s official calculated mileage (calculated under the official EU-regulated test conditions) and what you can actually achieve while driving.
MPG figures can still be used for comparison purposes, but they won’t be very helpful if you’re trying to determine how much a car will actually cost you, because the average miles per gallon in the real world will differ from the manufacturer’s value.
The amount of gasoline you’ll need for 100 miles will always be different on the road because the test removes variables such as hills, uneven road surfaces, and does not account for different driving styles, passenger weight, cargo carried, wind resistance, or any modifications made to a car.
For example, fitting larger wheels means the car will be heavier, generate more aerodynamic drag, and have more rolling resistance than standard wheels, so your car’s fuel economy will be worse.
HOW TO CALCULATE ACCURATE FUEL CONSUMPTION RATES
Even though the test is not entirely reliable, it is possible to calculate fuel costs yourself. It’s relatively simple and can teach you how to reduce fuel consumption and save money.
The simplest way is to fill up your car’s gas tank and note your current mileage. Decide whether you’re going to focus on urban, extra-urban, or general fuel consumption and drive normally under the desired conditions. When you’re ready to calculate your car’s MPG, fill up the tank again and note the number of liters of fuel it took to fill to the limit, as well as the number of miles traveled since the first fill-up.
Since we fill our tanks in liters, we’ll need to convert this figure to gallons. So, divide the mileage by the number of liters used, then to convert to MPG, multiply it by 4.546. You now have the true MPG of your car.
It’s important to note that if you want to compare it to the official statistics, you should try to stick to their test conditions (including the speeds used and the types of roads you’re testing on). All of this can be made easier if you have a built-in or aftermarket onboard computer. Many of them often automatically display the MPG at the end of a trip.
TIPS TO IMPROVE YOUR FUEL ECONOMY
From how you drive to what you keep in your car, here are 10 tips to reduce your fuel costs:
- Lighten your car: Get rid of all unnecessary items in the trunk or back seat of your car. For every 45 kg of weight in the vehicle, your car’s fuel economy decreases by about one or two percent.
- Keep your tires properly inflated: Underinflated tires can reduce your car’s fuel economy by up to five percent in some cases due to their insufficient traction on the road and increased resistance. Ensuring they are at the recommended pressure can save you money.
- Observe the speed limit: This is not only related to safety, because observing the speed limit also helps you maintain good fuel economy. Driving faster often means your fuel consumption will be worse because the engine has to work harder to produce the power needed for high speeds.
- Avoid idling: When your car is running but not moving, your gasoline mileage is absolutely zero, but fuel is still burned to keep the engine running. So, if your car is going to be stationary for more than about a minute, turn off the engine. However, only do this if you can do so safely.
- Regular braking and acceleration: While driving, always apply steady and constant pressure to your car’s accelerator pedal. A heavy foot will always lead to reduced gasoline mileage and low fuel consumption.
- Make your car more aerodynamic: Removing roof racks and reducing the car’s weight by removing unnecessary items or changing tires or rims can allow the car to move through the air better and reduce drag, meaning it takes less fuel to get you where you need to go.
- Use cruise control on highways: Cruise control means your car will go at a constant speed, meaning there is no acceleration. The absence of acceleration reduces the amount of work your engine does and thus consumes less fuel.
- Keep the windows closed: This can be difficult if it’s very hot outside, but keeping the windows closed makes your vehicle more aerodynamic and improves your car’s energy efficiency. Especially at higher speeds, you should keep the windows closed to reduce drag and improve fuel consumption.
- Use air conditioning less: There will always be times when you need to turn on the air conditioning, but you should try to use it in moderation.
- Replace dirty air filters: A dirty air filter makes your car’s engine work much harder and has a real negative impact on your fuel economy. Make sure to follow the manufacturer’s recommendations to periodically change the air filter.