The petrol-electric hybrid engine that powers the Toyota Prius has been named Green Engine of the Year by an international panel of experts.

Judges said the Prius engine remains the world's leader in reducing emissions without compromising performance.

The Green Engine of the Year is for an engine designed with fuel economy as a priority and which employs intelligent technologies to reduce emissions.

The Green Engine category was introduced this year at the prestigious International Engine of the Year awards.

Toyota has been honoured 19 times since the awards were launched in 1999, including with 10 awards for Hybrid Synergy Drive, which powers the current-generation Prius.

The innovative petrol-electric hybrid engine won four categories in 2004, including International Engine of the Year, two categories in both 2005 and 2006 and one each in 2007 and 2008.

Toyota Hybrid Synergy Drive combines a 1.5-litre petrol engine with a compact and powerful electric motor.

It gives Prius an unmatched combination of low emissions and excellent fuel economy.

Prius is the cleanest production family car in the world, emitting just 106g/km of carbon dioxide. It has an official combined cycle fuel consumption of 4.4 litres/100km*.

Toyota was also honoured for the second year running for its light and compact three-cylinder 1.0-litre VVT-i engine, which features in European models.

The International Engine of the Year awards are decided by a panel of 65 motoring journalists from 32 countries.

The 2008 winners were announced at a ceremony at Engine Expo 2008 in Stuttgart, Germany.

Engine of the Year Awards - Toyota

2008
Green Engine of the Year: Toyota Hybrid Synergy Drive (Prius)
Sub-1.0 litre: 1.0 VVT-i

2007
Best Fuel Economy: Toyota Hybrid Synergy Drive
Sub-1.0 litre: 1.0 VVT-i

2006
Best Fuel Economy: Toyota Hybrid Synergy Drive
1.4-litre to 1.8-litre: Toyota Hybrid Synergy Drive

2005
Best Fuel Economy: Toyota Hybrid Synergy Drive
1.4-litre to 1.8-litre: Toyota Hybrid Synergy Drive

2004
Best New Engine: Toyota Hybrid Synergy Drive
Best Fuel Economy: Toyota Hybrid Synergy Drive
1.4-litre to 1.8-litre: Toyota Hybrid Synergy Drive
International Engine of the Year 2004: Toyota Hybrid Synergy Drive

2002
1.4-litre to 1.8-litre: Toyota 1.8-litre VVTL-i 190

2000
Best Eco-friendly: Toyota Hybrid (previous-generation Prius)
1.0-litre to 1.4-litre: Toyota 1.3-litre VVT-i

1999
Best Eco-friendly: Toyota Hybrid
Sub-1.0-litre: Toyota 1.0-litre
1.4-litre to 1.8-litre: Toyota Hybrid
International Engine of the Year 1999: Toyota 1.0-litre