Electric vehicle (EV) supporters have touted developing high-speed charging technology as the way forward for cars like Nissan Motor Co's Leaf. But Yoshikazu Tanaka, chief engineer of Toyota's hydrogen fuel-cell car Mirai, said that would guzzle so much energy at once as to defeat the purpose of the EV as an ecologically sound form of transportation.

"If you were to charge a car in 12 minutes for a range of 500 km (310 miles), for example, you're probably using up electricity required to power 1,000 houses," Tanaka told a small group of reporters at the first test-drive event for the production version of the Mirai, the world's only mass-market fuel-cell car.

"That totally goes against the need to stabilise electricity use on the grid."

Even as rivals such as Nissan and Volkswagen AG promote battery EVs, cars like the Leaf require lengthy charging, reducing their attractiveness for customers planning to drive longer distances frequently. The Leaf requires about eight hours for a full charge using a 200-volt outlet, giving a listed driving range of around 84 miles in the United States.

"Toyota isn't denying the benefits of EVs," Tanaka said. "But we think the best way to use them is to charge them at night (to avoid peak power consumption hours), and use them for short distances during the day."

Instead, Toyota says hydrogen fuel-cell vehicles (FCVs) offer the most promising zero-emission alternative to conventional cars since they have a similar driving range and refuelling time.

While FCVs require massive investment and government subsidies for fuelling stations, Tanaka noted that hydrogen - the most abundant element in the universe - could be extracted from many different sources and had the advantage of being portable and more easily stored than electricity.

He noted that the southern Japanese city of Fukuoka last month completed a fuelling station that uses hydrogen made from sewage and that could power about 70 Mirai FCVs a day.

"Of course, there are technological hurdles that need to be cleared to make this commercially viable," he said.

"But remember 'Back to the Future'? In that movie, a car from 30 years in the future comes back to the present - the year 1985," he said, referring to the flying Hollywood time machine that was powered by garbage.

 "The Mirai doesn't fly, but this year, 2015, is that future."