HWASEONG, South Korea -- Aiming to make electrified cars a pillar of its portfolio, Hyundai Motor Co. says the technology is evolving so fast that it must roll out new electric vehicles on a two-year cadence to boost the current 110-mile range to around 250 miles by 2020.

The breakneck product cycle is being driven not just by upcoming competition from the Tesla Model 3 and Chevrolet Bolt, but from a blitz of upstart Chinese rivals whose EVs will be sold mainly in China.

Ahn Byung-ki, director of eco-vehicle development at Hyundai Motor Group, said the rate of technological improvement in electrified vehicles has been slow over the past six years, but that innovation will quicken in the face of pressure and demand from China.

"Electrical vehicles are changing real fast. From a conventional perspective, two years or maybe a year-and-a-half is not really a long time," Ahn said in an interview last week at the carmaker's Namyang r&d center here south of Seoul. "But in the EV business, it is a pretty long time. We have to be ready for the new generation every two years."