Gas-electric Lexus SUV is quiet, zippy

Nothing to plug in
A driver doesn’t do anything but drive the RX 400h. As with all hybrids, there’s no need to plug in the electric motors. Power for them is generated on-board as the vehicle travels and is stored in a nickel metal hydride battery that fits under the rear seat cushions.

The V6 has a confident sound when it's accelerating and isn’t heard much at other times. I did hear a bit of a “whirring” sound at times in the RX 400h when the electric power was flowing, the radio was off, and there wasn’t much other noise around the vehicle to mask the sound. And, because the RX 400h can be so quiet, I noticed some wind noise emanating from around the side mirrors at highway speeds.

The RX 400h is 375 pounds heavier than its gas-only counterpart, in large part because of the battery pack.

Handling is a bit trickier at the extremes in mountain twisties, because the battery weight makes the vehicle feel as if three fat guys are sitting in the back seat, as one auto writer colorfully put it. But in day-to-day travel, drivers are more likely to notice an occasional lightness to the steering — it's an electric power steering system for energy efficiency.

Not really for off-road
Note that the all-wheel drive is for improved on-road traction and for mild stuff like dirt paths. The hybrid RX is not an SUV for strenuous off-road duty. The reason? The rear electric motor will shut down before it burns itself out in rough situations such as a driver trying to climb over huge rocks or slog through mud.

There are other differences between the RX 330 and the hybrid. Mild styling changes include a revised grille to better channel air for cooling purposes. Taillamps have energy-efficient light-emitting diodes (LEDs).

Since a tachometer doesn’t really provide useful information in a hybrid, where power is mixed and matched among engine and electric motor sources, this gauge is replaced by a power meter in the instrument cluster. And rear seat cushions are positioned a tad higher than in the RX 330, so the hybrids batteries are accommodated.

A large display in the middle of the dashboard can show, via an automated graphic, where the power for the RX 400h is being generated and where it's going as the vehicle travels. It's a similar graphic to the one in the Prius.

Silent startup
The test RX 400h was so quiet at startup, I didn’t always know it was on. This is because the engine doesn’t need to start up right away. This hybrid can go a short distance on oh-so-quiet electric power only. Thank goodness that the RX 400h instrument cluster told me the vehicle was “ready” for driving, so I didn’t just sit there, wondering what to do.

Available & upcoming hybrids DaimlerChrysler Diesel-electric Dodge Ram: Pickup gets 15 percent mileage boost. 2008: Dodge Durango SUV with 25 percent mileage improvement. Ford Escape Hybrid: SUV rated at 36 in city driving with two-wheel-drive model, nearly double that of the gas-only Escape. Highway driving rated at 31 mpg. Mercury Mariner SUV: 33 mpg in the city, 29 on the highway. 2007: Mazda Tribute SUV, no mileage data yet. 2008: Ford Fusion and Mercury Milan sedans, no mileage data yet. General Motors GMC Sierra/Chevrolet Silverado: 2WD models get 18 mpg city, 21 mpg highway for an increase of 10-12 percent over gasoline siblings. Saturn Vue: SUV rated at 27 mpg in city and 32 mpg highway — a 20 percent increase over gasoline sibling. 2007: Saturn Aura sedan, no specs available. Chevy Tahoe, GMC Yukon, up to 35 percent mpg boost. Chevrolet Malibu, 15 percent increase. 2008: Chevy Silverado and GMC Sierra pickups that get up to 35 percent mpg increase. Honda Insight: two-door rated at 56 mpg on highway and in city but discontinued starting in 2007 model year. Civic Hybrid: four-door rated at 51 mpg on highway and 49 mpg in city. Accord Hybrid: rated at 35 mpg on the highway, 29 mpg in the city. Nissan Fall 2006: Hybrid version of midsize Altima. Toyota Prius: Sedan rated at 60 mph in city, 51 mpg on highway. Lexus RX 400h: SUV rated at 31 mpg in city driving, two thirds more than its gas-only RX 330 sibling. Highlander Hybrid: SUV is rated at 32/27 mpg in city/highway driving based on two-wheel-drive model. Lexus GS 450h: Sports sedan rated at 25 mpg in city and 28 mpg highway, along with 339 horsepower. Camry Hybrid: Sedan rated at 40 mpg in city, 38 on highway.

Lexus officials said they could be tapping into an undercurrent of buyers who do not want a big, brutish and flashy SUV that guzzles gasoline, even if they have the money to afford one.

Company officials expect about half of the RX 400h buyers to be women, with the median age of buyers likely to be 45 to 55. Three-quarters will be married, and three-quarters will have a college education. Median household income is expected to be from $150,000 to $200,000 a year.

As of early March, the company had 12,700 pre-sold orders, which accounts for 45 percent of the annual RX 400h allocation of 28,000. “This is significantly more pre-launch volume and activity than we have ever had this early for any vehicle in our 15-year history,” Clements said. Built in Japan, the RX 400h also will be sold in Japan and Europe.

The National Highway Traffic Safety Administration does not have crash test results for this new vehicle. Because the RX 400h is a new model, Consumer Reports does not report a reliability rating.

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