# 3 ways to calculate fuel consumption

As the price of fuel goes up all the time, more and more drivers are aware of how much their cars need. While the exact consumption of a car changes based on circumstances (city or highway, track conditions, tire pressure, etc.), knowing how much fuel yours uses is actually very simple.

## Steps

### Method 1 of 3: Determine Fuel Consumption

#### Step 1. You have to know that the equation to obtain gasoline consumption is "the number of kilometers driven divided by the amount of gasoline used"

The fuel consumption of a car is a measure of the kilometers traveled by each liter of fuel. If you know the distance you traveled and the number of liters going into your tank, you can simply divide the number of kilometers by gasoline to get your measurement of "kilometers per liter" or km / L.

• You can perform the same calculation with miles and gallons.
• The best time to check in is right after filling your car with gas.

#### Step 2. Reset the "trip odometer" after filling your tank

Most modern cars have an odometer that can be set to zero at any time. It is usually on the dash or center console and with the help of a small button you can reset it to zero. Do it when you fill the tank and check it when you fill it up again, this number will be your mileage since the last time you bought gas.

• If you don't have one, record the number of miles on your car as the "starting mileage." For example, if your car has 10,000 miles (16,000 kilometers) driven when you fill the tank, write this number.

#### Step 3. Record the kilometers shown on the trip odometer just before you buy more gas

Before you start filling up your car at the gas station, record the mileage shown on the odometer as "final mileage."

### If you don't have a trip odometer, subtract "starting mileage" from your current mileage to find out how far you've traveled. For example, if your odometer shows 16,495, subtract 16,000 from it. You will have driven 4,495 kilometers on a tank of gas

#### Step 4. Drive your car until the tank is almost empty

You can perform the calculation no matter how much gas you still have in your tank, but the more you have used, the more accurate the reading will be.

#### Step 5. Record the amount of gasoline you bought in liters

Refill the tank completely and write down how many liters or gallons you need to achieve this. This amount will be your "fuel usage".

### For this step to work, you need to fill your tank completely or you won't know how much gas your car has used since the last fill

#### Step 6. Divide the mileage by the fuel usage to find out what your car's consumption is

This figure will tell you the number of kilometers you traveled per liter of gasoline. For example, if you drove 335 miles (539 km) before heading back to the gas station and then filled the car with 12 gallons (45 L) of gasoline, your fuel consumption would be 27.9 miles per liter (11.9 km per liter). gallon) or km / L, since 539 km / 45 L = 11.9 km / L.

• If you did the calculation in kilometers and liters, you must divide the fuel used by the kilometers traveled and multiply the result by 100 to obtain “liters per 100 kilometers”.
• You have to start with a full tank and have it again with the same measurement to know exactly how much gas your car has consumed.

#### Step 7. Practice the calculation with an example

Let's say Jose's odometer reads 23,500 miles (37,819 km) with a full tank. After driving for a few days, you will have to buy gas. The odometer now reads 38,445 km (23,889 miles) and it takes 47 L (12.5 gallons) to refill the tank. What will your fuel consumption be?

• Fuel consumption = (final mileage - initial mileage) / fuel usage
• Fuel consumption = (38 445 km - 37 819 km) / 47 L
• Fuel consumption = 626 km / 47 L
• Fuel consumption = 13.31 km / L

### Method 2 of 3: Know Your Average Fuel Consumption

#### Step 1. Remember that fuel consumption changes depending on the way you drive

For example, turning your car off and on multiple times uses much more gas than driving at a steady pace. This is the reason why consumption on roads is always lower than in the city.

• Fuel consumption worsens the faster you drive.
• Since the air conditioning system uses gasoline, turning it on will increase your fuel consumption.

#### Step 2. Record several full tanks of gasoline to find out what your average fuel consumption is

To get a more accurate idea of the consumption of your car, you will need more data. Driving for longer periods and finding your average fuel consumption eliminates any "glitches" in your data.

### For example, let's say you calculated your fuel consumption one day when you were driving to the mountains. As going uphill uses more fuel, your consumption will look much higher than it actually is

#### Step 3. Reset your trip odometer to zero with a full tank of gas

Zero your tool and don't reset it after filling the tank. If you don't have an odometer, record how many miles your car reads when the tank is full.

#### Step 4. Record the number of liters of gasoline you buy each time you fill the tank

To get a more accurate measure of your fuel consumption, you need to know how much gasoline you use. Every time you fill the tank, write down the number of liters you bought and put it away.

#### Step 5. Drive normally for several weeks

Don't reset the odometer when you're driving, and make sure to fill your tank 3-4 times to get an accurate reading. Try to do it in a month of average trips, as long trips or unexpected traffic will change your fuel consumption.

### You don't have to fill your tank completely every time you go to the gas station. You can calculate fuel consumption as long as you record the number of gallons you put in it

#### Step 6. Fill your tank after 2-3 weeks

When you are ready to calculate your fuel consumption, fill the tank and record the number of liters you put in it.

#### Step 7. Add the number of liters you bought

This number represents the total amount of gasoline you used during this time period.

### If you bought gasoline three times, say 12, 3, and 10 gallons (45, 11, and 37 L), then your total usage will be 25 gallons (93 L)

#### Step 8. Divide the total kilometers by the total liters

Use your odometer to see how many kilometers you have traveled in total, then divide this amount by the liters to get your average fuel consumption. Although this is the same number of kilometers per liter during your test period, it is a good estimate of the average fuel consumption of your car.

### For example, if you use 25 gallons (94.6 L) of gasoline and drive 500 miles (804.6 km) during that time, then your average fuel consumption will be 20 miles per gallon (8.5 kilometers per liter); i.e. 804.6 km / 94.6 L = 8.5 km / L

#### Step 9. You have to know that the mileage advertised by companies for your car is generally overestimated

By law, car brands must publish the average fuel consumption of those they sell. However, these amounts are only estimates and are generally close to the upper range. You can search what is the fuel consumption of your car on the Internet by means of? of this website of the United States Ministry of Energy, but to really know what the kilometer per liter of your car is, you will have to do the calculation yourself.

### Method 3 of 3: Maximize Your Fuel Consumption

#### Step 1. Avoid air conditioning

It uses gasoline to cool your car, which means you will have less fuel to drive. Reduce or turn off the air conditioning once the car is cool to make it more efficient.

### Running the air conditioning on top can lower your fuel economy by almost 25%

#### Step 2. Drive within the speed limits

The faster you drive the car, the more fuel it will consume. As in the previous case, it is not a minimal variation. For every 8 km (5 miles) that you travel at more than 80 km / h (50 m / h) you will have to pay about \$ 0.19 more for every 4 liters of gasoline. Keep in mind that this amount will vary according to the price of gasoline in your country.

#### Step 3. Drive defensively

Starting to move a car takes more energy than continuing to move it. This means that if you follow other cars closely, turn the car on and off, or try to pass them frequently, you will use more fuel than if you were keeping a steady pace.

### Try not to brake or accelerate sharply. Brake early instead of stepping on the pedal

#### Step 4. Use the cruise control to drive on long, flat stretches

This function keeps the car at a constant and uniform speed, which avoids unnecessary fuel consumption at minimum accelerations and stops.

#### Step 5. Turn off your car in traffic

Leaving the car idle or running when it's not moving wastes gas without you going anywhere. Whenever you can, turn off the engine to save your precious fuel.

#### Step 6. Avoid roof rack racks

These devices greatly decrease its aerodynamics, which slows it down and consumes more fuel. In general, the most efficient options in terms of consumption are the trailer and the trunk.

#### Step 7. Have your tires well inflated

When all four tires are low, gas mileage can decrease by 0.3%. Use the free air pump found at most gas stations and inflate them to the psi level recommended in your car manual.

### Some cars indicate the proper tire pressure on a sticker located on the driver's side door or in the glove compartment

#### Step 8. Change your air filter

This is one of the cheapest and simplest methods to increase fuel efficiency. You should buy the right filter for your car, so take details like make, model, and year to your local auto parts store for recommendations as all vehicles need a different filter.