Toyota unveils an all-new, third-generation Prius hybrid sedan for 2010, with upgrades in just about every area of the vehicle. Slightly larger, better equipped, more powerful, and more fuel efficient than the version it replaces, the 2010 Prius hybrid retains the previous generation's same basic exterior design, building on the popularity and easily recognized triangular shape of a car that has sold more than 1.2 million units worldwide since its introduction more than 10 years ago. The new Prius, however, has a more aerodynamic exterior design, with better airflow along its roofline and corners, a flat underbelly, and a slightly lengthened tail, all of which help reduce wind resistance and improve fuel economy numbers.

According to Toyota, the 2010 Prius midsize sedan posts a combined fuel economy number of 50 mpg (up from 46 mpg combined for the previous-generation Prius), making it the most fuel-efficient production vehicle currently available in the U.S. Those fuel-economy numbers split out to 51 mpg in the city and 48 mpg on the highway. However, many early reviewers and test drivers report much higher fuel economy numbers of anywhere from the mid-60s to more than 80 mpg, depending on road conditions, local terrain, and driving styles.

The new Prius achieves those impressive numbers not only with its aerodynamic exterior design, but also with its more fuel-efficient hybrid engine. Toyota updated more than 90 percent of the Prius's Hybrid Synergy Drive powerplant, which now includes an all-new, beltless 1.8-liter Atkinson-cycle four-cylinder gas engine, replacing the previous year's 1.5-liter engine. The new four-cylinder produces more low-end torque while ensuring optimal fuel efficiency by operating at lower speeds than the previous year's engine. The Hybrid Synergy Drive also includes two electric motors (MG1 and MG2), which combine with the gas engine to generate a total of 134 hp. The powerplant drives the Prius from 0 to 60 to 9.8 seconds.

As in previous years, the Prius can run on the gas engine alone, the electric motor alone, or a combination of the two. In addition, the powerplant operates at lower rpms at highway speeds for a more "relaxed" driving experience, according to Toyota, and delivers improved up-hill performance. The automaker also updated the Prius's regenerative braking system, which charges the battery when the driver applies the brakes.

Aiding the powerplant's efficient operation are three new driver-selectable operating modes - Eco, EV, and Power. Each mode results in more or less gas pedal responsiveness, with resulting fuel usage or savings. Eco Mode provides maximum fuel economy, while in EV Mode the Prius operates solely on battery power for up to one-half mile, conserving fuel. The Power Mode provides a sportier, more responsive driving experience.

Drivers can monitor the operation of the Hybrid Synergy System via a real-time digital readout on the instrument panel, which displays the current battery charge level, the current selected mode of operation, fuel consumption, and the flow of energy from the gas engine to the electric motor, among other details.

Toyota has equipped the Prius with a number of new features for 2010. An optional sliding glass moonroof, for instance, comes equipped with integrated solar panels, which power a new ventilation system without assistance from the engine. The ventilation system keeps the interior of the Prius from becoming too warm when the car is parked, which shortens cool-down time when the driver starts the engine.

Another new feature, called the Touch Tracer Display, projects a virtual image on the instrument panel of the multi-function steering wheel's audio and information buttons when they're pressed by the driver. This helps keep the driver's attention focused forward instead of down toward the steering wheel. Other new fetures include optional LED headlights, which use less energy than typical headlights, and an available pre-collision system, which adjusts the brakes and front seatbelts in the event of an imminent accident.

Thanks to its slightly larger profile, the 2010 Prius offers more interior space than the previous year's version, including more cargo space and more legroom in the rear seats. Seat cushions, some interior trim, scuff plates, and other interior components are made with eco-friendly plastics, which emit less carbon dioxide during their life cycles and manufacture. Toyota also added new interior silver accents and storage spaces, among other features.

Standard safety features include a new Dynamic Radar Cruise Control System, which maintains a set distance behind the vehicle in front, and an available Lane Keep Assist system, which helps keep the driver safely within the lane. In addition, a next-generation Intelligent Parking Assist system helps drivers guide the car into parking spaces.

Finally, thanks to an upgraded platform, the new Prius handles better in corners and exhibits less body roll than the previous-year's version. Updated seats are also said to be more comfortable and more supportive for the driver and passengers, especially under tight cornering.