Hyundai Boosts Performance of Sonata Hybrid Powertrain

The hybrid drive offered in Hyundai Motor Co.'s 2013 Sonata sedan is equipped with a 35-kW motor that is 17% more powerful than last year's unit.

The system's redesigned 47-kW lithium ion battery is smaller but provides one-third more storage capacity. The upgrade enables the car to capture more energy from its regenerative braking system and travel farther solely on electric power.

Most current hybrid systems couple a gasoline engine to two electric motors through a planetary gearbox, which serves as a constant-velocity transmission. Hyundai's single motor architecture connects a single motor to the piston engine through a 30% faster-acting electrically actuated clutch but retains the standard model's six-speed automatic transmission.

The configuration enables the Sonata hybrid to operate in electric mode at speeds as high as 75 mph. Conventional hybrid systems are designed primarily to improve powertrain efficiency at lower speeds, notes John Juriga, director of powertrains for Hyundai of America.

The 2013 Sonata hybrid has a city/highway fuel economy rating from the U.S. Environmental Protection Agency of 36/40 mpg. The combined rating of 38 mpg is up by 2 mpg from last year's adjusted number. Juriga says drivers may see better highway economy than EPA's relatively low-speed test cycle indicates.