Washington - US carmaker General Motors' big green hope, the Chevrolet Volt, will use just one litre per 100 kilometres in city driving according to initial tests, chief executive Fritz Henderson said Tuesday.

Unveiling a series of new models that GM hopes will revive its sagging fortunes, Henderson said its flagship Volt was on track to enter production in late 2010. GM's one- time German subsidiary Opel will introduce a companion European model, the Ampere, in 2011.

The plug-in hybrid Volt will be able to drive about 60 kilometres on its electric battery alone. A petrol engine with a 55-litre tank can recharge the battery while driving, extending its range by as much as 1,000 kilometres.

The battery can also be recharged overnight by plugging it into an electric outlet, and Henderson said he expected most consumers would not have to use any petrol most days.

In comparison, Toyota's Prius, one of the most gas efficient cars on the road, uses about 4.6 litres per 100 kilometres in urban driving.

US car sales have plummeted since October by more than 35 per cent amid a deep recession. Domestic manufacturers have been especially hard-hit as consumers turned to greener, smaller cars offered by foreign rivals.

Henderson said the Volt "can and will be a game-changer" for General Motors Co, which emerged from bankruptcy last month under the majority control of the US government.

If the tests hold up, GM's Volt would be about four times as fuel- efficient as Toyota Motor Corp's Prius, which has dominated the hybrid car market for the past decade.

But the technology is still in its infancy and the car will also be much more expensive than current hybrids, costing as much as 40,000 dollars according to previous GM estimates.

The Prius by contrast costs about 25,000 dollars. A similar hybrid introduced by Honda this year, the Insight, costs less than 20,000 dollars.(dpa)