Toyota Unveils 50mpg Rated Third-Generation Prius Hybrid

January 13, 2009 by Jeff Shepard

Toyota Motor Corp. is unveiling its 2010 Hybrid Prius, which it claims is rated to 50mpg. The company claims that the midsize third-generation Prius will offer even better mileage ratings and enhanced performance. The vehicle will can also be equipped with a moonroof that has solar panels.

Using a combination of technologies, fuel efficiency was increased to an estimated 50mpg for the new Prius. A larger and more powerful 1.8-liter Atkinson-cycle, four-cylinder engine will power the new Prius. Contrary to conventional wisdom, the larger engine actually helps improve highway mileage. By making more torque, the new engine can run at lower average rpm on the highway. When operating at lower rpm, the new engine uses less fuel. Mileage is especially improved in cold-start conditions and at higher speeds.

Use of an electric water pump and a new exhaust gas recirculation (EGR) system also contribute to the engine’s efficiency. The 1.8-liter Prius engine is the first Toyota power plant that requires no belts under the hood for better fuel economy and less potential maintenance.

The patented Hybrid Synergy Drive system in the 2010 Prius is 90% newly-developed with significant improvements over previous models. The transaxle is lighter in weight and reduces torque losses by as much as 20% compared to the previous model. The inverter, which converts direct current to alternating current, has a new direct cooling system to reduce size and weight. Taken together, the inverter, motor and transaxle are smaller and 20% lighter. A newly developed electronically controlled regenerative braking system has been adopted, with control logic optimized to enhance regeneration.

An available sliding glass moonroof is packaged with solar panels, located over the rear seating area, that power a new ventilation system. This solar powered ventilation system uses an electrically powered air circulation fan that does not require engine assist. The system prevents the interior air temperature from rising while the vehicle is parked, making the cool-down time shorter when the driver returns to the vehicle, thus reducing the use of air conditioning.

The remote air-conditioning system is the first system in the world to function on battery-power alone and that can be remotely operated, so the driver can adjust the interior temperature for comfort before getting in the car.

Reducing the vehicle’s power consumption, available LED (light emitting diode) lamps are used for low beams and also in the tail and stop lamps. Air conditioning, a major energy drain, has been re-engineered to increase efficiency and cool-down performance. In addition, an exhaust heat recirculation system reduces heat waste by warming engine coolant during cold startup, for improved performance. It also heats up the passenger cabin more efficiently.

The 2010 Prius has a permanent magnet synchronous motor with a power output of 80 hp/153 lb-ft torque. Interestingly, Toyota has chosen to use a nickel-metal hydride battery for the battery pack.