YOUNTVILLE, CA --- When it launches this spring, the all-new 2010 Toyota Prius will offer a combined EPA estimated fuel efficiency rating of 50 miles per gallon.

According to Toyota, the midsize third-generation 2010 Prius will offer better mileage ratings, enhanced performance, and innovative design features. It will be quieter, roomier, and equipped with advanced standard and available features such as a moonroof with solar panels, four driving modes, Intelligent Parking Assist (IPA) and steering wheel touch controls that display on the instrument panel.

"The Prius has evolved with our customers over the past 10 years and is now more things to more people," said Bob Carter, group vice president and general manager for Toyota Division.

Prius entered the market in 1997 as the world's first mass-produced hybrid. From the beginning, Toyota's full-hybrid system was developed almost entirely in-house. The Hybrid Synergy Drive System was introduced in 2004 on the second-generation Prius. Since then, more than 700,000 have been sold in the U.S.

The new Prius will be built using processes that reduce pollution in every stage of vehicle life -- from production and driving through to disposal, Toyota said. Using a combination of technologies, fuel efficiency was increased to an EPA estimated city/highway mpg rating of 50 in the city, 49 on the highway and a combined 50 mpg.

A larger and more powerful 1.8-liter Atkinson-cycle, four-cylinder engine will produce 98 horsepower at 5,200 rpm in the new Prius. Together with its electric motor, the hybrid system will generate a combined net horsepower of 134, an improvement of 24 horsepower over the previous generation.

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.

A multi-information display panel that monitors fuel and energy consumption is standard. It provides feedback on the Prius' efficiency using three different displays to help the driver acquire economical driving habits.

The patented Hybrid Synergy Drive system in the 2010 Prius is 90 percent newly developed with significant improvements over previous models, Toyota said. The transaxle is lighter in weight and reduces torque losses by as much as 20 percent 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 percent lighter. A newly developed electronically controlled regenerative braking system has been adopted, with control logic optimized to enhance regeneration.

The new Prius will offer three alternative driving modes. EV Mode allows driving on battery power alone at low speeds for about a mile, if conditions permit. There is also a Power Mode, which increases sensitivity to throttle input for a sportier feel, and an Eco Mode, which helps drivers achieve their best mileage.

The new Prius will be certified as a Super Ultra Low Emission Vehicle (SULEV) and an Advanced Technology Partial Zero Emissions Vehicle (AT-PZEV) in California, as well as those states adopting California emission standards. The AT-PZEV certification requires the SULEV exhaust standard linked with the ability to meet a zero-fuel-evaporative standard, a 150,000-mile durability demonstration, extended emissions system warranty, and technology deemed by the California Air Resources Board (CARB) to advance future fuel cell vehicles.

In the rest of the country, Prius will be certified as Tier 2, Bin 3. The new Prius will produce over 70 percent fewer smog-forming emissions than the average new vehicle.