Office of Energy Efficiency

Natural Resources Canada's Office of Energy Efficiency provides advice and financial assistance - including grants - to individuals and organizations to reduce energy use.

The ecoENERGY for Personal Vehicles program maintains fuel economy information on vehicles. This information is used to: advise consumers, determine which vehicles receive government rebates, and which ones are subject to low mileage taxes. This data is significantly different than the EPA equivalent [http://www.fueleconomy.gov/feg/FEG2000.htm Gas Mileage Guide] . For example, according to transport Canada, a 2007 Chevrolet Malibu Maxx with a V6 engine and a manual transmission obtains 39 mpg highway. The EPA reports 28 mpg highway for the same make and model.

Canadian results also appear to have no correlation with actual mileage. For example, a 2007 automatic transmission KIA Spectra vehicle is reported with 46 mpg highway by Natural Resources Canada, while actual owners report an average of 31 mpg.

The reason why actual mileage and test mileage is so different can be explained.

Firstly, in Canada, imperial gallons have been used, rather than US gallons. To compare with the US mpg, the conversion factor of 235 is divided by the L/100km. This will be 20% lower than imperial mpg.

Secondly, vehicles have gasoline in the engine and gas lines at any time. This is why if your tank is on empty, you can still drive a short distance. Canadian mileage tests are done for 16-km on a programmable laboratory dynamometer (treadmill). Since only two wheels are spinning, it is relatively trivial for the electronic control module of a 4-cylinder, two-wheel drive car to detect these test conditions and "borrow" approximately 10 ml per km of gas out of the engine rather than the tank; it's a little like having a spare tank. Eventually, this borrowed gasoline needs to be returned to the engine, something that does not happen during the test. You can usually correct for this test-condition factor just by adding 1 L/100km to the test results listed with the vehicle. A different correction factor is needed for hybrid vehicles and vehicles with more than 4 cylinders which is not discussed here.

For example, [http://oee.nrcan.gc.ca/transportation/personal-vehicles-initiative.cfm Personal Vehicles Initiative] list a manual transmission 2007 Honda Fit Wagon with mileage of Hwy 5.8 L/100km (49 mpg). First we note the correct mileage would actually be 1+5.8 = 6.8 L/100km. To convert this to US mpg, we simply take 235/(1+5.8) = 35 mpg. This is within roundoff errors of 34 mpg reported in the EPA [http://www.fueleconomy.gov/feg/FEG2000.htm Gas Mileage Guide] .

Another factor to be aware of is, that since only the drive wheels spin during the test, it is possible to minimize friction by using the electronic stabilization control system to shift the weight off the vehicle drive wheels. Also, the test fails to account for airflow. So, a car designed like a brick would perform equally well as a car NASA designs for optimal air flow in a wind tunnel.