Hybrid cars are booming in the US with sales rising 81 per cent last year, according to new figures.

New hybrid registrations in the US totalled 83,153 in 2004, according to figures released yesterday by automotive data firm RL Polk.

Since 2000, the hybrid market has grown by a massive 960 per cent.

Reasons for the boom are thought to include US tax breaks for fuel efficient vehicles as well as consumer belief that driving a hybrid is more socially responsible.

Hybrid vehicles are powered by internal combustion engines but also are equipped with batteries that are recharged while driving and an electric motor to assist with power. They typically cost $3,000 to $4,000 more than traditional models.

While US company Ford debuted its Escape hybrid model last year, Japanese automakers currently dominate the market in the US, accounting for over 96 per cent of registered hybrids.

Major automakers are said to be planning on introducing about 12 new hybrid models during the next three years. Models to be introduced this year alone will include the Lexus RX400h, the Mercury Mariner and the Toyota Highlander SUV.