Toyota Motor Corp said on Friday its improved FCHV zero-emission fuel-cell car completed a road test from Osaka to Tokyo, covering 560 km (350 miles), on a single tank of hydrogen.

The latest version of the FCHV features a high-pressure tank of 70Mpa that can store double the amount of hydrogen as its previous fuel tank, increasing its cruising range. Two cars were tested and both completed the trip, the automaker said.

Most big automakers are working on developing fuel-cell vehicles, which use a chemical reaction between hydrogen and oxygen to generate electricity and emit only water. But high costs, infrastructure and storage safety issues mean they are years away from practical use.

With the new tank and high-performance fuel-cell stack, the FCHV has a potential single-fuelling range of about 750 km (466 miles), making it 25 percent more fuel-efficient than earlier versions, it said.

Hyundai Motor Co, South Korea's top automaker, said a day earlier it planned to begin mass production of its fuel cell car model from as early as 2012.

General Motors Corp, a leading proponent of the powertrain, has said it will likely have fuel-cell vehicles in showrooms by 2012.