Ford Motor Co. is offering free upgrades to U.S. and Canadian hybrid customers to improve their fuel economy.
The company plans to recalibrate the vehicle control systems on 77,000 Ford C-Max and Fusion hybrids and Lincoln MKZ hybrids from the 2013 model year.
Some customers have complained that the cars aren't getting the 47 mile-per-gallon fuel economy promised in Ford's advertising.
Ford will increase the maximum speed the cars can be driven in electric mode from 62 to 85 miles per hour.
It also plans to make better use of the grille shutters, which improve aerodynamics; reduce the electric fan speed; shorten the engine warm-up time and minimize use of the air conditioning compressor.
Ford will notify owners next month. It won't say how much it's spending on the upgrades.