All cars that come to the market have to certify a series of parameters. For example, their emissions per kilometer or their safety in accidents.
Autonomy is another one of those key values that manufacturers must provide before receiving approval from official agencies. But in this case, they need a third party to validate their tests.
Today we explain how they calculate the range of a car in the United States, whether it is a gasoline or an electric one.
The beginning of EPA mileage tests
The EPA (United States Environmental Protection Agency) began testing vehicle fuel consumption in 1971, and those initial tests continue to play an important role in how modern cars are measured.
The previous year, President Richard Nixon signed the National Environmental Policy Act of 1969 (followed by the Clean Air Act of 1970) and established the EPA with a mandate that included reducing motor vehicle emissions.
Part of the EPA’s plan to reduce emissions was to inform buyers about the amount of fuel a car would consume so they could compare prices effectively.
The tests began with a route called the Federal Test Procedure. The EPA adopted an 11-mile (18 km) route that was originally made on real roads in Los Angeles. The route had an average speed of 34 km/h (21 miles per hour) and a maximum speed of 90 km/h (56 mph). Exhaust emissions were measured, fuel consumption was calculated, and the “city” fuel consumption rating was born.
When the 16 km (10 mile) road consumption test was added in 1974, the tests were conducted on a laboratory dynamometer. Conducting the tests on the power bench made them more consistent and easier to repeat, although it was not perfect.
Over the years, small changes and adjustments were introduced, but the most important change was announced in 2005. That year, the EPA announced changes to the test to adapt it to new highway speeds, take into account the use of heating and air conditioning, and make it more in line with real-world driving.
The drivers were not able to achieve the published figures, and the EPA wanted to fix it. The system was introduced for the 2008 model year and is largely the one we use today.
Electric cars autonomy test
Nowadays, car manufacturers have two different testing options for electric vehicles.
The manufacturer may decide to perform a “single cycle” test. In this test, the car goes through the EPA urban cycle over and over again until the charge is depleted, and then does the same for the highway cycle, starting with a full charge. The process is repeated to check reliability.
The alternative is for the car manufacturer to perform a multi-cycle test that completes four cycles in the city, two cycles on the highway, and two cycles at a constant speed.
