Prestige Subaru

Does your car's fuel economy (mileage) drop in the winter?

 
We get lots of questions from customers regarding their fuel economy, especially in winter.  There are several reasons that a vehicle's "miles per gallon" fall during winter months:

1.)  "Winter Mix Fuel"  Winter mix fuel contains a different additive package than traditional summer mix fuel, this can be one reason for fuel economy losses.

2.)  Colder / more dense air.  Computer controlled vehicles base the amount of fuel they inject into the engine on the air coming in.  Cold air is more dense, and therefore requires more fuel to mix and cause a proper burn (that will meet EPA requirements) which also can reduce fuel economy numbers.

3.)  "Warming up/ Defrosting" the car.  One of the most overlooked reasons for a loss of fuel economy is warming up the car, especially in the morning.  Starting your car and allowing it to idle to warm up for only 10 minutes per day for 5 days can reduce the average miles driven per tank by almost 50 miles.

All these factors combined can cause significant (and in some cases) alarming drops in fuel economy. 


If you suspect that your vehicle's fuel economy has dropped, we suggest the following test procedure:

1. Fill the vehicle with fuel at your normal fueling station.  Make sure
that when the pump automatically shuts off, you DO NOT top off or add any additional fuel. 

2. Reset your trip odometer to Zero.

3. Drive the vehicle until it is 3/4 empty or less.

4. Refill the vehicle at the SAME station, and once again, stop filling
immediately when the pump automatically shuts off.

5.  Note the amount of fuel required to fill the tank (in gallons) and
enter that number below at   A.

6.  Record the mileage showing on your trip odometer and record
that below at   B.

7.  Divide the miles driven by the number of gallons required to refill
and enter that below at   C, this is your average miles per gallon.


Example:


A.     12.45 gallons

B.       285 miles

C.       22.89 MPG