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How government fuel economy ratings are determined
by Jim Kerr
So you're ready go new car shopping. You have selected several vehicles that meet your needs, but fuel economy is important too. The fuel economy numbers look good on the window sticker, but are they really accurate? How do they test them?
Canada and the U.S. use similar Federal Test Procedures (FTP) for testing the fuel economy of new vehicles. Each test is a standardized laboratory test method where a trained driver drives the vehicles on a dynamometer for a predetermined drive cycle. The test is structured so that each vehicle is driven under identical conditions and that the results for each vehicle are consistent.
Two different tests are used. One tests fuel economy for city driving and the other for highway driving. Actually, the FTP tests are used to certify the vehicles to emission standards, but the fuel economy can be calculated by measuring the carbon compounds emitted during the test.
The fuel economy estimates are printed on the new vehicle window sticker as well as the annual estimated cost of fuel the vehicle would use if driven a distance of 20,000 km with 55% city driving and 45% highway driving. Of course, with the recent surge in fuel prices, those annual fuel costs on the window stickers are now long out of date and it could be some time before things stabilize and the data is close again.
The Canadian FTP city test simulates a 12-kilometre stop-and-go drive lasting 23 minutes. The drive begins after starting a cold engine, to simulate a vehicle parked overnight. It includes 18 stops, four minutes of idling time, a maximum speed of 91 kph and an average speed of 32 kph. When the test is completed, the first 8 minutes of the test are repeated starting with a hot engine to simulate a vehicle that has been stopped momentarily and then restarted.
The U.S. city test simulates an 11-mile (17.7 km) stop-and-go drive lasting 31 minutes. Like the Canadian test, the engine is started cold. It includes 23 stops with 18% (about 5
by Jim Kerr
So you're ready go new car shopping. You have selected several vehicles that meet your needs, but fuel economy is important too. The fuel economy numbers look good on the window sticker, but are they really accurate? How do they test them?
Canada and the U.S. use similar Federal Test Procedures (FTP) for testing the fuel economy of new vehicles. Each test is a standardized laboratory test method where a trained driver drives the vehicles on a dynamometer for a predetermined drive cycle. The test is structured so that each vehicle is driven under identical conditions and that the results for each vehicle are consistent.
Two different tests are used. One tests fuel economy for city driving and the other for highway driving. Actually, the FTP tests are used to certify the vehicles to emission standards, but the fuel economy can be calculated by measuring the carbon compounds emitted during the test.
The fuel economy estimates are printed on the new vehicle window sticker as well as the annual estimated cost of fuel the vehicle would use if driven a distance of 20,000 km with 55% city driving and 45% highway driving. Of course, with the recent surge in fuel prices, those annual fuel costs on the window stickers are now long out of date and it could be some time before things stabilize and the data is close again.
The Canadian FTP city test simulates a 12-kilometre stop-and-go drive lasting 23 minutes. The drive begins after starting a cold engine, to simulate a vehicle parked overnight. It includes 18 stops, four minutes of idling time, a maximum speed of 91 kph and an average speed of 32 kph. When the test is completed, the first 8 minutes of the test are repeated starting with a hot engine to simulate a vehicle that has been stopped momentarily and then restarted.
The U.S. city test simulates an 11-mile (17.7 km) stop-and-go drive lasting 31 minutes. Like the Canadian test, the engine is started cold. It includes 23 stops with 18% (about 5
