Trip computers that display average fuel economy and an estimated distance to an empty tank may be off by 6% or more, AAA found.
In a study conducted at the Automobile Club of Southern California’s Automotive Research Center, AAA discovered discrepancies as high as a 6.4% overestimated fuel economy and as low as 2.2% underestimation.
Similarly, the “miles to empty” readout accuracy varied between vehicles. That estimation of a vehicle’s range until its tank is empty is based on a manufacturer-specific algorithm that looks at recent driving habits. Even with the same amount of fuel remaining in a tank, recent aggressive driving with hard acceleration will assume the driver will burn through the rest of the tank quickly. In contrast, gentle driving at moderate speeds will trigger a higher distance to empty reading. The algorithms assume drivers will continue to operate the vehicle similarly to recent operation.
AAA did not state which vehicles it tested using the Automotive Research Center’s dynamometer, kind of an automotive treadmill allowing a vehicle to operate at high speeds on rollers without physically moving. Such devices are commonly used for emissions testing.
Your mileage may vary, after all.
This story originally ran on Autotrader.com.