Sporty handling and responsive engines make the Nissan Altima fun to drive. Yet this fourth-generation Altima is more refined than the pre-2007 model.

Fuel economy is aided by the CVT, or continuously variable transmission. Altima is EPA-rated 23/31 mpg City/Highway with the four-cylinder, 19/26 mpg with the powerful V6 (premium fuel required). The Nissan Altima 2.5 S we drove had plenty of power from our perspective. Modern and refined, Nissan's 2.5-liter four-cylinder engine delivers 175 horsepower. Called the QR25DE, this engine was refined for use in this fourth-generation Altima, with a larger intake manifold, increased compression ratio, and reduced internal friction. It features continuously variable valve timing, microfinished crank journals and cam lobes, molybdenum-coated lightweight pistons, and an electronically controlled (drive-by-wire) throttle.

The 3.5-liter V6 makes a potent 270 horsepower and is a very close relative to the 3.5-liter V6 in the sports car. There's more than enough here, and it's awesome for passing. Its 6,600-rpm redline is a blast. There's also 258 pound-feet of torque, which was very useful with the CVT transmission.

The 3.5 SL suspension is quite firm and we found it delivers responsive handling. There's no swaying in switchback turns, so the steering stays true. And it wasn't harsh over the jagged parts of the road. It took some good punches from potholes without flinching. Altima's stiff chassis helps keep noise and vibration down in the cabin, though we could hear the front wheels whacking bumps. The electric power steering, a speed-sensitive rack-and-pinion, works well, and because it uses less power than a hydraulic system, it improves gas mileage by a touch. Torque-steer in the Altima is extremely mild, which is saying something at 270 horsepower.

We drove a Nissan Altima 3.5 SE with the six-speed manual gearbox, and the linkage didn't feel exceptional, which makes the CVT seem especially like the best of both worlds.

The CVT used in the Altima is the fourth generation of this continuously variable transmission, which doesn't have the separate gears of a standard automatic transmission. Nissan has been a leader in this technology. The manual mode makes allows shifting ratios, making it feel like a six-speed.

We love the Altima's CVT because it's true to us. It's totally responsive and obedient. It did things that the manual modes in some expensive cars (Mercedes-Benz and BMW, to name two) have apparently never dreamed of. It listened to the driver. We challenged it by up-shifting all the way up to sixth gear at no more than 30 miles per hour, then downshifting back down, and it made every shift instead of ignoring them, unlikely as they would have been under regular driving conditions. So, when we used it in the real world, shifting the Altima like a 350Z on the road from the Golden Gate Bridge to Stinson Beach, it was beautiful. Downshifting with the CVT to slow down worked well, complementing the good brakes when rushing up to those downhill curves.

Brakes are vented discs in front and solid discs in the rear. All 2008 Nissan Altima models come with four-channel, four-sensor ABS with Electronic Brake force Distribution (EBD), which optimizes the front/rear brake balance depending on load condition (passengers and cargo). A variable-ratio-pivot brake pedal provides a rigid feel at freeway speeds and less sensitive, more controllable operation in city driving.

The Altima Hybrid is EPA-rated at 35/33 mpg, an excellent fuel economy rating, comparable to the 34/34 mpg rating for the .

The Hybrid uses a somewhat de-tuned version of the 2.5-liter four-cylinder, rated 158 horsepower at 5,200-6,000 rpm, and 162 pound-feet of torque at 2,800-4,800. Mounted in tandem with it is a permanent-magnet AC synchronous motor-generator that can produce up to 40 horsepower and 199 pound-feet, both at 0-1,500 rpm. So, potentially, that totals a substantial 198 horsepower and 261 pound-feet of torque.

Such high torque at low rpm allows the Altima Hybrid to start from a dead stop using only the electric motor to accelerate. So precisely where a conventional internal combustion vehicle is operating at minimal efficiency, the Altima Hybrid isn't using any gasoline at all. After the electric motor provides initial acceleration, the gasoline engine quietly starts and shoulders most of the load. Eventually the electric motor shuts off, and the gasoline engine does what it does best, which is constant-speed cruising. Then, when required, the electric motor restarts to give the gas engine some help in, say, passing situation. Helping provide smooth acceleration with maximum economy is the Altima Hybrid's specific CVT automatic transmission, called eCVT, which works in conjunction with the master control system to determine which power source or combination of power sources will turn the wheels. The Hybrid uses regenerative braking to recharge its 245-volt nickel-metal hydride battery, so you never have to plug it in. The Altima's hybrid technology comes from Toyota and has proven to be reliable.

A digital display in the speedometer indicates when the Altima Hybrid is running solely on electric power. The Altima Hybrid's available DVD navigation system also features a real-time display showing how the hybrid system directs the flow of energy.