Toyota has introduced new systems and engineering aspects, improving the fuel and emissions performance of the fourth generation Prius by 18%.
Already one of the most thermally efficient petrol engines, Toyota has further improved the Atkinson Cycle engine. New piston and air intake port designs create more swirl in the cylinder and reduce the need for exhaust gas recirculation. There's also low-viscosity oil to reduce the friction between moving elements.
A new cooling system reduces the flow of coolant within the engine and uses the coolant water selector valve to hurry the engine warm up process. This improves fuel efficiency in the winter by reducing the amount of time the engine takes to reach operating temperature.
The 97hp, 1.8 VVT-i unit now achieves thermal efficiency figures of 40%, compared to the 25% average for petrol engines and 35%-40% average for diesel engines.
The Hybrid technologies have been made smaller and lighter, with the 71hp electric motor, transaxle, the power control unit and the hybrid battery all shrinking. The new power control unit has around 20% smaller losses than the previous unit, while the reduced size and weight of these components allows more freedom with location.
The auxiliary batteries have been relocated to the engine compartment form the trunk, as well as the repositioning of the hybrid battery that originally lived beneath the back seats, which frees up luggage space and boot capacity. The hybrid battery itself is now made out of nickel-metal hydride to live up to market requirements.
The Toyota New Global Architecture (TNGA) chassis means the centre of gravity is lower for better handling, and also helps to advance safety - along with enhanced Toyota Safety Sense Features. The TNGA concept improves the frame’s rigidity by 60%, creating a steadier ride.