When it debuted two years ago, the Lexus RX 400h marked the beginning of a new paradigm by introducing more efficient hybrid technology to the popular but highly consumptive luxury SUV segment. While more affordable hybrid utilities from Toyota and Ford have been around for several years and other larger upscale SUVs from Chrysler and GM are now joining the hybrid parade, the 2008 Lexus RX 400h remains the lone "green" entry in the midsize luxury utility class.

Using full-hybrid technology, the RX 400h's gasoline/electric powertrain can operate in gas-engine-only, electric-only or combination modes depending on conditions. The system combines a V6 engine with an electric motor-generator to drive the front wheels and stores its energy in a nickel metal hydride battery pack that fits inconspicuously under the vehicle's rear seat. (All-wheel-drive models feature an additional electric motor to drive the rear wheels.) These components work together seamlessly to generate up to 268 horsepower and 0-60-mph sprints in fewer than 8 seconds. During light acceleration or when coasting, the 400h saves fuel by running solely on battery power. It all adds up to acceleration similar to that of some V8-powered rivals while achieving the best fuel economy in the midsize luxury SUV class.

Of course, none of this comes cheap. A typically equipped 400h will cost close to $50,000, about $4,000 more than a similar RX 350. Even with gas above $3 a gallon, it will take many miles and years of driving to recoup the cost. And from a pure "save the planet" standpoint, buying a Prius still makes much more sense. That said, this is still one very likable vehicle. Quick, fuel efficient and luxurious, the RX 400h comes with a set of attributes that just about any luxury SUV buyer will find appealing.

The 2008 Lexus RX 400h is a midsize luxury SUV available in front- or all-wheel-drive versions. It comes in one trim level with standard and optional equipment levels much like the RX 350. Standard equipment includes 17-inch wheels, a power rear liftgate, 10-way power front seats, cloth upholstery, sliding and reclining second-row seats, dual-zone climate control, multifunction steering wheel controls, heated outside mirrors and eight-speaker premium audio with an in-dash six-CD changer.

Many popular optional features are available separately or in packaged groups, such as the Premium Package which includes leather trim, a power tilt-and-telescoping steering wheel, driver seat memory settings and a sunroof. A Premium Plus Package offers these items plus adaptive xenon headlights. Other RX 400h options include 18-inch wheels, a fantastic 11-speaker Mark Levinson audio system, a navigation system with back-up camera, a rear-seat entertainment system, satellite radio and specialized interior wood trim.

The Lexus RX 400h hybrid combines a 3.3-liter gasoline V6 engine with electric motor-generators to power vehicle systems and the driving wheels. Front-wheel-drive models use two motor-generators -- one acting as a starter and the other providing motive force -- while the all-wheel-drive version adds a third electric motor to drive the rear wheels. Producing up to 268 horsepower and working through a specialized continuously variable transmission (CVT), Lexus claims the front-drive RX 400h can go from zero to 60 mph in 7.5 seconds and an even quicker 7.3 seconds for all-wheel-drive models. Towing capacity is 3,500 pounds when properly equipped, same as the RX 350.

EPA-estimated fuel economy is superior to that achieved by gas-only V6 or V8 competitors. Rated at 27 mpg city and 24 mpg highway, the front-drive RX 400h is also as efficient (or more so) than many smaller four-cylinder sport utilities.

Standard RX 400h safety equipment includes front seat-mounted side airbags, a driver knee airbag and rollover-sensing front and rear head curtain side airbags. Antilock brakes, stability control and traction control are also included. Adaptive cruise control is available as an option, as is a rear back-up camera that's included with the optional navigation system. In government crash tests, the 2008 Lexus RX 400h scored a perfect five stars in frontal- and side-impact testing.

The 2008 Lexus RX 400h drives a lot like its gas-powered RX 350 sibling, delivering both a smooth ride and reasonably tight handling despite its extra weight (which is noticeable when changing directions at higher speeds). That smooth ride comes thanks to soft suspension tuning, which makes the RX feel a little too spongy for those who appreciate a more spirited driving experience. However, the electric motor at least offers peppy acceleration and quiet operation under normal driving conditions -- the 400h is capable of approaching 30 mph in electric mode alone, which is of great fuel-saving benefit in stop-and-go traffic. Under maximum acceleration, though, a substantial amount of engine noise is apparent as the hybrid system forces the relatively small V6 to work harder and rev all the way up to redline. One other downside is that many drivers find the RX 400h's brakes grabby and difficult to modulate.

The Lexus RX 400h is as sleek inside as it is outside, seating five in a streamlined and high-tech interior that boasts aluminum or wood trim, bright-ringed gauges and a high-resolution touchscreen that displays the hybrid powertrain's gas-electric power distribution. The 40/20/40-split rear seat folds, slides and reclines to optimize passenger comfort and cargo-carrying versatility. A standard power liftgate opens up to reveal more than 38 cubic feet of luggage space and approximately 85 cubic feet of maximum cargo room with the rear seats folded, both competitive numbers for its class. A third-row seat, a feature often found in this vehicle segment, isn't available.