Toyota's main target with the next version of the Prius, which first went into production in 1997, is to improve on the 50mpg US combined average mpg (approximately 60mpg UK mpg) achieved by the current, third-generation model.
To attain this, it will use batteries with a higher energy density than those installed in the current Prius, as well as an electric motor that is smaller in size and features an improved power density and an internal combustion engine with a world-best thermal efficiency of more than 40 per cent – compared to the 38.5 per cent achieved by the 1.8-litre powerplant in the current third-generation car.
The current Prius electric motor provides four times the power density of the first iteration, and the next Prius's power density will be even higher.
Toyota Motor Corporation’s managing officer, Satoshi Ogiso, said: “These new hybrid powertrains will deliver significantly improved fuel economy in a more compact package that is lighter in weight and lower in cost.
“The performance of this new generation of powertrains will reflect significant advances in battery, electric motor and petrol engine technologies.
"It is part of Toyota’s larger strategy towards the electrification of the automobile, including plug-in hybrid, battery electric and fuel cell technologies. Toyota has a deep commitment to vehicle electrification and therefore, to advancing drive-battery technology."
Ogiso wouldn't be drawn on how much he expected the Prius's fuel economy would improve. He likened the difficulty of the challenge of making significant mpg gains to Usain Bolt shaving time off his 100-metre sprint world record, in as much that incremental improvements are more realistic.
The next Prius, which is expected to reach the market in two to three years, will also benefit from new mechanical underpinnings, said Ogiso, who was part of the team that started development of the original Prius back in 1993.
“To complement the substantial gains in powertrain development the next Prius will ride on a vastly improved chassis," he said. "It will feature the Toyota New Global Architecture (TNGA). It will have a lower centre of gravity and increased structural rigidity. This, along with many other improvements, will allow for beneficial gains in ride and handling agility and aerodynamics.
“Its interior will be roomier with significant refinements in design, layout and ease of operation, and it will introduce key advanced safety technologies."