Although these are pre-homologation figures, it the most efficient versions of the Prius will fall into the 9% BiK band and be exempt from the London Congestion Charge – one of only two models to achieve this without plug-in technology. The other is the Yaris Hybrid.  

Toyota says the efficiency gains are the result of improving the thermal efficiency of the 1.8-litre petrol engine – in other words reducing the energy lost as heat during the combustion cycle – as well as modifying the transmission.

The electric part of the drivetrain includes a more compact, more energy-dense nickel-metal hydride battery and a motor which now provides more assistance while accelerating, which reduces the springy quick-rev, slow acceleration characteristics of the old car. For the first time, the Prius can tow an unbraked trailer of up to 725kg.  

Toyota has also improved the rigidity of the bodyshell by 60%, as well as improving aerodynamics to reduce fuel consumption. It’s claimed that this makes the latest Prius more fun to drive.   

First UK deliveries are due next March, and Toyota says there will be some variation depending on trims available in each country and final homologation.