"I know some of the automotive world have been negative on fuel cell vehicles but other automakers as well as Toyota are moving forward with this technology," Jim Lentz said in a speech ahead of the annual North American International Auto Show.

Toyota unveiled a fuel cell concept sedan at the Tokyo Motor Show in November. The car, which features two hydrogen tanks and a driving range of about 500 km (310 miles), will sell for 5 million to 10 million yen ($48,000 to $96,000) when it goes on sale in 2015, Toyota has said.

Lentz reiterated Toyota's forecast for the entire U.S. market to grow modestly to around 16 million vehicles in 2014, "leveling off" after posting strong growth of more than 7 percent last year.