For 2010, the hybrid mechanicals were lightened by 65 pounds and made stronger.But the Prius still gained 110 pounds overall, mostly from its stiffer body structure.The 1.8-liter gas engine was new, more powerful and efficient.Top speed flew up to 112 miles per hour from 103 mph, on aerodynamic improvements.Acceleration performance is lethargic: 0 to 60 mph in 9.8 seconds.The CVT, or continuously variable transmission, is smooth.

There are three driving modes: EV, ECO and Power.EV is all electric, for very short distances at speeds under 25 mph; ECO provides the best fuel mileage, without noticeably compromising performance; and Power, the default mode, is needed for brisk acceleration.

For 2012, there will be a PHV model, or plug-in hybrid; it's a standard Prius with extra batteries that provide an all-electric range of 13 miles after a three-hour charge at home.We drove a prototype around town for one week, and got about 11 miles to a charge, but the range might be increased for the production model.

Driving the Prius is easy.Handling is easy if not nimble at slow speeds, and the brakes are sensitive while being stacked with electronic capabilities for safety.The ride feels stiff, most noticeable over jagged slow bumps, and interior noise is surprisingly high despite increased sound insulation.Many owners might not notice, but others will, those Prius buyers in search of tranquility.

In the back seats, there's 36 inches of legroom, not great for a midsize car, though we view the Prius as a compact car, and the 60/40 split rear seats have a folding center armrest with two cupholders, for when there's not a third passenger back there.

Cargo space is generous with nearly 40 cubic feet of capacity when the back seats are dropped flat, and the big liftgate makes loading easy.

Technology is in abundance.The Touch Tracer Display projects information before your eyes, so you can keep them on the road.Input comes from the pilot at the controls on the steering wheel, including not just audio and cruise control, but also climate control and trip computer, with telephone and other controls available.A solar-powered ventilation system is available, with remote pre-cooling to cool the car down to ambient temperature before you climb in on a hot day.There's a warning beep when you're unsteady in your lane; radar cruise control; Intelligent Parking Assist that will parallel park the Prius with no steering or throttle input from the driver; and pre-collision emergency braking to slightly reduce the impact when you don't see an accident coming but the car's radar does.

The 2010 Prius was recalled for the accelerator pedal getting trapped under the floor mat, which was fixed with a modification to the shape of the pedal; and a second time because a relatively few owners complained about the way the brake pedal felt when the ABS was activated, so software was changed.Both these changes are on the 2011 model.On the brake issue, Toyota took a bum rap because nothing was found to be wrong except the drivers' experience, not to mention the media blow-up.

Prius II ($23,050) is fully equipped and is expected to be the most popular.Along with the Touch Tracer display, it includes cruise control, rear wiper, tonneau cover, and four-speaker AM/FM/CD with MP3/MWA capability.

Prius III ($24,050) adds a premium six-speaker JBL sound system with 6CD, Bluetooth and a rearview camera.The Navigation Package ($1,930) includes touchscreen, rearview camera, voice-activated DVD navigation with Bluetooth, XM traffic.The Solar Roof Package features a solar powered ventilation system.

Prius IV ($26,850) adds leather seats and upgraded trim, heated front seats, water repellent window glass, plasma instrument cluster, HomeLink, and a Smart Key system for three doors.Navigation with Safety Connect is optional.

Prius V ($28,320) adds 17-inch alloy wheels, LED headlamps, and foglamps.The Advanced Technology Package ($5,080) features a pre-collision system that automatically dabs the brakes and reduces crash impact speed by a slight amount, radar cruise control, Lane Keep Assist, Intelligent Park Assist, and the Navigation Package.

Safety equipment standard on all models includes dual-stage front airbags, side airbags in front, airbag curtains, and driver's knee airbag; active headrests; tire pressure monitor with warning light; anti-lock brakes with Brake Assist and Brake Force Distribution; and a sophisticated stability control system working with traction control.Optional safety equipment includes a pre-collision system that uses the same radar antenna as the radar cruise control.It applies the brakes harder than the driver does if a collision is imminent and applies them even if the driver doesn't to reduce the collision impact by 0.7g.

The upper grille opening is smaller and tidier to more efficiently move air over the hood.A new lip over the rear deck not only improves air flow, it eliminates the chopped-off-tail look of the previous Prius.The fender arches are a bit more aggressive, almost bulkier looking, but they reflect additional aero improvement.The bumpers are sharper and squarer at the corners than before.You can't see the underbody covers with splitters, but they too are part of the aerodynamic scheme, to achieve that 0.25 Cd.

The blue-tinted headlights are elegant wraparound trapezoids, with optional LED lenses consuming 17-percent less battery power.There's a styling tweak, like a wave or a lip or, with a stretch of the imagination, a lightning bolt at the top, and it works, to deliver distinction.The taillights are standard LED, reducing power draw by 88 percent.

The rear wiper is huge, and effective in keeping rain off all that glass back there.The matt black trim around the windows on the Prius II and III trim levels doesn't do much to complement the car; the satin black finish on the Prius IV and V is nicer.

The front seats are comfortable with good bolstering and adjustability.The trim looks nice, ecologically friendly plastic made of plant-derived resin with excellent recycling characteristics.The upper and lower gloveboxes hold a magnificent 12 liters.

There's 36 inches of rear legroom, not bad at all, and the 60/40 split rear seats have a folding center armrest with two cupholders, for when there's not a third passenger back there.

When the seats are dropped flat, there's nearly 39.6 cubic feet of cargo volume, easily accessible through the big liftgate.We hauled seven 16-inch wheels shod with Dunlop racing tires in the back.The eighth had to ride in the front seat, but we were impressed with the cargo capacity.

And there's another 2 cubic feet in the tray for tools and laptops, hiding under the floor of the cargo area.The compact spare tire is another level down.A tonneau cover for the cargo area is standard.

There's good forward visibility even over the long dashboard, stretched by the steeply sloped windshield, although, as with other aero cars (the Honda Fit comes to mind), you can't see the front corners.And visibility out the rear glass is compromised by the aerodynamically sloped roofline and the bar that separates the two pieces of glass.

The four-spoke steering wheel with many controls is interesting and not ugly.It's fun to watch the multi-function display of the instrument panel, although the novelty might wear off.On a 5-inch screen, there are graphs and images, including an Energy Monitor, displaying the battery charge in real time; a Hybrid System Indicator that reveals the efficiency of your driving technique; fuel mileage in 1- or 5-mile increments; past fuel mileage; and a Touch Tracer Display that projects steering-wheel-control information upward so you can keep your eyes on the road.Curiously, the USB port isn't standard equipment.

The Hybrid Synergy Drive system, with two compact motor generators within the transaxle, delivers operating voltage of 650V.It uses gear drive, allowing the motor to turn 13,500 rpm.The Power Control Unit (inverter) is compact.The Nickel-Metal Hydride battery pack is compact and powerful.The accessory drive belts have been eliminated, with such things as the AC compressor and water pump now driven electrically.This means the air conditioner works, though not full blast, even with the engine turned off.

There are three driving modes: EV, or all-electric, with a very limited distance at 25 mph or less (if there's enough juice in the battery), most useful for underground parking garages; ECO, which minimizes fuel consumption by reducing the throttle opening and restricting the air conditioning; and Power for full acceleration.

The difference between Power and ECO is 4.1 seconds from 50 to 70 mph, versus 5.8 seconds.If you're in ECO and floor it, it will kick itself into Power, which is also the default mode when you start it up.So you have to set ECO mode at every stop, to get the best mileage.But we wonder why anyone would drive around town in Power mode, because ECO feels no slower.The Prius accelerates from 0 to 60 mph in 9.8 seconds, usually fast enough though slow by modern standards.

When you accelerate hard and it kicks into Power mode, it can be abrupt, like a transmission kick-down.But like all hybrids it uses a CVT, continuously variable transmission, which is technically not an automatic because it doesn't have gears.Most of the time you're not aware the Prius CVT is there, which is how they're supposed to work.

The Prius is EPA-rated at 51 city and 48 highway, for a combined 50 miles per gallon.We got 54 mpg driving gently but still sometimes using Power mode, over 23 miles of city-highway driving; and later 70.5 mpg over a 34-mile street course in a competition with other automotive journalists.We averaged 28 mph, about average for the group.

The winner, a specialist hypermiler, got 94.6 mpg driving by all the tricks.He averaged 19 mph, moving at about 30 mph in the far right emergency lane of the 50-mph highway, showing that it takes travel in an unreal world to achieve those big numbers.An opposite leadfoot extremist managed to get 26.8 mpg.The other 26 of 28 drivers got between 63.3 and 75.3 mpg.

Later, during our one-week drive of the prototype PHV, we got 41.8 mpg for about 180 miles, 26 of them on full electric, and most of the rest at 65-70 mpg in Power mode.

One flaw in the Prius is its bumpy ride: pretty rough over patchy stuff, we noted during our test drive.The suspension was given a slightly wider track and increased roll rigidity for 2010.The pre-2010 Prius didn't feel as harsh.The 15-inch wheels are fitted with low-rolling-resistance tires (195/65R15), and maybe that explains it.

We also drove a Prius with the optional 17-inch wheels and 215/45R17 tires, which felt slightly smoother although theoretically they should be firmer; we got better mileage with them, 57.4 mpg, although the Prius chief engineer said the 17s deliver about 5-percent less mileage.

We thought road noise was high.

The four-wheel disc brakes are sensitive, and we could hear rubbing at low speeds with ours, partly because there was no engine noise when backing off, and possibly because of the regenerative braking component: the more you use the brakes, the more battery juice you build up, enabling you to use EV mode more.On our 70.5-mpg run, we gently used the brakes a lot in city traffic, so we would get as many blocks as possible out of EV mode.

The handling is light enough around town, but out on the road, if you try to drive it aggressively in corners, it turns heavy and slow.The slower you drive it, the better it is.That said, cornering is much improved over pre-2010 models with the redesigned chassis and suspension.

We tested the optional Intelligent Parking Assist, part of the Advanced Technology Package available for Prius V, which parallel parks the car for you, if the space is big enough.It needs a margin of 7 feet 9 inches, more than half the length of the car; most drivers can handle a space that big with no worries, so it's fair to ask what's the point, unless you're not at all competent at parallel parking (and we know skilled race drivers who fit that description).Like many high-tech innovations, it does it because it can.You can set the distance you desire to the curb.Pull up, line up, press the button, it tells you when to go; then release the brake pedal and take your hands off the steering wheel and let it do its thing.

Sam Moses filed this report to NewCarTestDrive.com after his test drive of the Prius in California's Napa Valley and of a Prius PHV prototype near Portland, Oregon.