Evolution: the plug-in Toyota Prius is set to go on sale next year

The most popular hybrid in the world is the Toyota Prius with 1.5m cars sold since it was launched in 1997. It came to Europe in 2000 and is still a work in progress as significant improvements to successive evolutions continue in the third generation.

A new, lightweight 1.8-litre petrol engine has replaced the 1.5-litre unit and power output has been increased by over 30% to 136bhp while fuel consumption has been reduced by over 23% to only 3.9l/100 km (72.4mpg), and CO2 emissions reduced by almost 26% to just 89 g/km – a best-in-market figure.

The combination of internal combustion and battery power has won many friends for Toyota and now we are about to get a plug-in Prius which you can charge from the family domestic electricity overnight to give between 12 and 20 miles of pollution-free driving on electric power.

With rivals such as Mitsubishi set to launch electric cars this year Toyota realises that the limit of driving on battery power has to be extended. So the plug-in hybrid is to get a bigger battery and an upgraded electrical system. Using a domestic supply the battery can be fully recharged in 100 minutes and will continue to charge on journeys when the brakes are applied.

Toyota say that the 1.8 litre petrol engine with the 346 volt electric motor can give significant extra take-off power and an economy on battery power of over 100 mpg.

The plug-in Prius models are on test and Toyota say that if you stay below 100 km/h the engine should not cut in and even if it does the switch from battery power to engine power is very smooth. The engine can drive the Prius directly if you put your foot hard on the accelerator, or charge the battery to extend the range of the electric-only driving.

With new developments in battery technology the future looks bright for plug-in models which will soon have a comfortable commuting range for driving pollution-free in urban areas, with the back-up of petrol or diesel power for the longer journeys.

Plug-in models are expected to go on sale next year and will be more expensive than the current model which has a price tag of just under €26,000.