The third-generation Toyota Prius hybrid is getting the finishing touches before its debut at the Detroit motor show next January. It will go on sale in the UK late next year.Sources say that the new hybrid will be larger than today’s car but still be recognisable as a Toyota Prius. Crucially, though, it will be greener and better to drive than today’s globally successful model.The hatchback will be about 10cm longer and 3cm wider than today’s car and, to cope with the bigger size, the engine will move up from 1.5 to 1.8 litres. Power should increase to 100bhp.Toyota says it can achieve this higher output while still improving economy and lowering emissions. Sources in Japan claim that Toyota is aiming for a 12 per cent improvement in fuel consumption, leading to a combined economy of over 70mpg and C02 emissions of just over 90g/km.Toyota’s trademark hybrid system will be more tightly packaged and efficient, ensuring that the car is able to run longer on pure battery power.At launch the Prius will stick with the current style of nickel metal hydride batteries, but the ‘smarter’ style of lighter, high output lithium-ion batteries may arrive by 2010. The first plug-in versions of the Prius are likely to go on limited release at the same time.The Prius hatchback pictured here will be part of a range of hybrid models that Toyota intends to launch to with a Prius badge.One of these could be a minivan based on the Hybrid X concept from Geneva 2007.