The only luxury hybrid SUV on the market is selling well even as sales of other midsize sport utilities are falling.

But the fact that consumers who can pay $45,000 and up for the Lexus RX 400h also would care about saving gasoline shows that perhaps even those who can afford higher gasoline prices aren’t particularly eager to spend more on fuel than they have to.

There has been a feeling among automakers that luxury cars would pretty much be exempt from the pressures on sales that higher fuel prices bring.

But sport utilities such as the Lexus RX line, typically purchased for everyday family use, might not quite fall into the luxury class, where operating costs are generally not an issue. In fact, the RX 400h price, which begins at just under $45,000 for a two-wheel-drive model, really isn’t all that high in today’s market, where a fully equipped GMC Yukon or Chevrolet Tahoe full-size SUV can cost even more.

The RX 400h has EPA ratings of 31 miles per gallon in the city and 27 on the highway, which puts it near the top of the SUV class overall, and well above vehicles such as the Lexus LX 470, with its ratings of 13 mpg city/17 highway.

Lexus also has made the RX 400h more affordable than it was when it arrived in April 2005. At first, it was offered only with all-wheel drive, with some amenities that were optional on the gasoline-only RX 330 model – such as a fancy navigation system with a rearview camera. The original base price was just under $50,000, about $12,000 more than a -ase version of the RX 330. Consumer demand prompted the company to roll out a less-well-equipped front-drive model, with a base price of $44,060, and an all-wheel-drive version, also with less standard equipment, for $46,060, Lexus spokesman Greg Thome said. With both of those, the navigation system is optional. And while sales of the RX line overall have fallen this year from last as sales of midsize luxury SUVs have tanked, the hybrid model is still about 23 percent of sales overall, close to the sales targets Lexus had projected for the vehicle, Thome said.

While industrywide midsize luxury SUV sales have fallen 17 percent this year through July, compared with the same period last year, the Lexus RX line is down just 2.6 percent for the year, buoyed by sales of the hybrid model.

“It has helped sales that people can now get an RX 400h for a lot less than they could at the start,” he said.

The $44,060 starting price now represents just a $7,000 premium over the base RX model for 2006. (Prices for 2007 have not been announced.)

The test vehicle provided to us by Lexus was one of the original all-wheel-drive models that came with the navigation system as part of the vehicle’s then-$48,535 base price (plus $650 freight). Ours had even a few more extras that ran the total sticker up to $52,703 (including freight). They included a DVD rear-seat entertainment system ($1,840); two-level heated front seats, packaged with headlight washers ($540); and an uplevel Mark Levinson audio system ($980).

The RX 400h looks almost identical to the regular RX, and the only indication it is a hybrid is the “RX 400h” badge on the tail. For 2007, though, the vehicle gets some hybrid badges, something consumers have said they wanted so their vehicles could more easily be recognized as hybrids, Thome said.

That’s in keeping with the demographics of the typical high-end hybrid buyers, who seem to choose the vehicle more for its “cool” factor than the fact that it has better fuel economy than similar gasoline-only models.

Besides the better fuel economy, the RX 400h has 90 percent lower smog-forming tailpipe emissions than conventionally-powered vehicles, Lexus says.

Similar to the Toyota Highlander hybrid – both are built on the same architecture and have nearly identical hybrid drive systems – the RX 400h “delivers greater performance, improved fuel efficiency and significantly reduces emissions while sacrificing none of its luxury or utility,” says Lexus, the luxury division of Toyota.

The two-wheel-drive RX 400h has a 3.3-liter V-6 gasoline engine with a high-torque electric drive motor-generator up front. The all-wheel-drive version has those elements along with a second electric motor driving the rear axle.

The all-wheel-drive model we tested had a combined 268 horsepower (gasoline engine and electric motors together), and 3,500 foot-pounds of axle torque at startup. The vehicle can accelerate from zero to 60 mph in 7.3 seconds, better than many of the hybrid’s V-8-powered competitors.

Besides the “RX 400h” badge, styling differences from the base RX model include a unique grille, front fascia with an additional air intake, round fog lights, special 18-inch alloy wheels and LED taillights.

Interior differences include special brushed-aluminum accents (replacing the gasoline model’s wood trim) and a power meter, which replaces the tachometer. Lexus says the RX 400h is a “full hybrid,” which means it can run on electric only, gasoline only or a combination of these.

The power steering pump, water pump and air-conditioning compressor are not driven by a belt from the gasoline engine. Instead, they are electrically powered. This allows them to continue functioning when the gasoline engine shuts down at idle or low speeds.

Powering the electric motors is a 288-volt nickel metal hydride battery pack under the rear seat. The batteries are automatically recharged as the vehicle slows down or coasts, or when it is running on the gasoline engine only.

Unlike electric cars, the hybrid does not require plugging into an external electric power source to recharge the batteries.

A third electric motor is used up front as a starter and does not deliver any power to the wheels. As with the other two motors, though, it doubles as an electric-power generator when the vehicle is coasting or braking.

This third motor can either charge the battery pack or provide power to the other two electric motors as needed, Lexus says.

A continuously variable automatic transmission is used to drive the front wheels. The separate 50-kilowatt electric motor at the rear of the all-wheel-drive model provides up to 650 foot-pounds of torque on demand, Lexus says.

Among high-tech safety features are a stability control system and electronically controlled braking.

Other safety features include seat-mounted side air bags for the front occupants and side-curtain air bags for front and rear passengers.

Unlike the Highlander, the RX 400h is offered with only two rows of seating, for a maximum of five people; the Highlander hybrid comes with a third seat and can hold seven passengers. Cargo capacity is 38.3 cubic feet behind the second seat, the same as in the RX 330. That can be expanded to almost 85 cubic feet by folding down the rear seat, which has a 40/20/40 split design. Among other standard features are rain-sensing windshield wipers and adaptive front headlights that shine in the direction the car is turning.

Other amenities include dual-zone automatic climate control; a 10-way power front driver’s seat with memory and an eight-way power passenger seat; a three-spoke steering wheel with controls for the audio system, trip computer and driver-information display; an auto-dimming rearview mirror with digital compass; power, heated, self-dimming outside mirrors; a power single-piece rear liftgate; a power tilt/telescopic steering wheel with memory; a one-touch power moon roof; an illuminated entry system that lights the door handles, scuff plates and front foot wells; and a universal garage/gate opener.

The optional Mark Levinson audio system has 11 speakers and a six-disc CD changer in the dash.

G. Chambers Williams III is staff automotive columnist for the San Antonio Express-News and former transportation writer for the Star-Telegram. His automotive columns have appeared regularly in the Star-Telegram since 1995. Contact him at (210) 250-3236; chambers@star-telegram.com.

At a Glance: 2006 Lexus RX 400h

The package: Premium, midsize, front- or all-wheel-drive, four-door, five-passenger, V-6 and electric-powered hybrid crossover sport utility vehicle.

Highlights: New for 2006, this is the first luxury hybrid SUV on the market. It offers a cornucopia of high-technology, along with superb fuel economy, great power, and low tailpipe emissions.

Negatives: No third-row seat offered; price climbs significantly with navigation and other extras.

Overall length: 187.2 inches.

Curb weight: 4,365 pounds.

Engine: 3.3-liter V-6; one or two electric drive motors.

Transmission: Continuously variable automatic.

Power: 268 HP (combined gasoline and electric).

Brakes, front/rear: Disc/disc, antilock.

Cargo volume: 38.3 cubic feet (rear seat in place); 84.7 cubic feet (rear seat folded).

Towing capacity: 3,500 pounds.

EPA fuel economy: 31 miles per gallon city/27 highway.

Fuel capacity/type: 17.2 gallons/unleaded regular acceptable, but premium recommended.

Main competitors: There are no other hybrid sport utilities in this class..

Base price: $44,060 (plus $650 freight).

Price as tested: $52,703 (all-wheel-drive model, including freight and options). On the Road rating: ***** (five stars out of five).