When the first Lexus RX hybrid debuted nearly a decade ago, it represented something rather unusual: a premium-brand SUV that sipped rather than swilled fuel. Modern times have seen many more automakers bringing their own fuel-efficient crossover SUVs to market. Still, the 2014 Lexus RX 450h does its forebear proud, as it ranks at the top of this now populous vehicle class thanks to its outstanding fuel mileage, comfortable cabin and lengthy standard features list.

Sporting a full hybrid system much like its Toyota Prius cousin (albeit with a lot more power), the RX 450h delivers an impressive EPA combined rating of 30 mpg. By comparison, most regular luxury crossovers post combined averages in the 20-23-mpg range. Even rival hybrid and diesel-powered models can't quite match the 450h's figures.

For motive muscle, the RX 450h features a 3.5-liter V6 paired to electric motors that are powered by a battery pack. The combination provides both the aforementioned high fuel efficiency as well as respectable performance. Beyond that, the 450h is a lot like the regular RX 350, which means comfortable seating for five, a plush ride and a handsome cabin featuring top-notch materials and assembly quality and many available high-tech features. As for downsides, there aren't many: The RX 350's biggest demerits are the lack of a third-row seat and an electronics interface that takes more of your attention to use than we expect.

If the availability of a third-row seat really is important to you, we'd point you toward the new 2014 Infiniti QX60 Hybrid. The QX's fuel economy isn't quite as good as the RX's, but otherwise it's a very family-friendly luxury crossover (and its third row easily accommodates adults). Beyond that, the RX 450h is more fuel-efficient and less expensive than rival hybrid-powered models, including the Audi Q5 Hybrid, Porsche Cayenne Hybrid and Volkswagen Touareg Hybrid. The same can be said if you put it up against the diesel-powered BMW X5 and Mercedes-Benz ML350. Overall, we think the RX 450h is an ideal choice for a fuel-efficient, five-passenger luxury crossover.

The 2014 Lexus RX 450h comes in just one trim level. Standard features include 18-inch wheels, automatic headlights, foglamps, LED running lamps, rear privacy glass, heated mirrors, a power liftgate and keyless ignition/entry. Inside you get automatic dual-zone climate control, a power tilt-and-telescoping steering wheel, eight-way power front seats with two-way power lumbar adjustment, reclining and sliding rear seats, cloth upholstery, a leather-wrapped steering wheel and auto-dimming mirrors.

Standard electronic features include the Safety Connect emergency communications system, Bluetooth phone and audio connectivity, Siri Eyes (enhanced hands-free iPhone functionality and integration) and a nine-speaker sound system with a six-CD changer, satellite radio, an auxiliary audio jack and an iPod/USB audio interface.

There are many optional packages available, some of which require the purchase of one to obtain another. The Premium package adds a sunroof, power-folding and auto-dimming mirrors, roof rails, leather upholstery and driver memory settings. There's also a version of this package that also includes a blind spot monitoring system. The Comfort package adds automatic wipers, xenon headlamps, and heated and ventilated front seats (also available separately).

The Display Audio package gets you a rearview camera, a larger 7-inch central display screen, Bluetooth phonebook download capabilities, the Lexus Remote Touch electronics interface, the Enform suite of app-based features and a 12-speaker sound system with HD radio. The Navigation package adds the Display Audio contents along with a navigation system (with 8-inch display) and voice controls.

Finally, the Luxury package adds 19-inch wheels, LED headlamps, 10-way power front seats, a heated wood and leather steering wheel, upgraded leather upholstery, a 115-volt power outlet for the rear seat area and smog-sensing, automatic climate control recirculation.

Other options include front and rear parking sensors, a head-up display, a dual-screen rear seat entertainment system, a 15-speaker Mark Levinson surround-sound audio system and adaptive cruise control with a pre-collision warning system (requires all-wheel drive).

Powering the Lexus RX 450h is a combination of a 3.5-liter gasoline V6 engine and electric motors. Front-wheel-drive models use two motors; one acts as a starter-generator and the other provides propulsion. The all-wheel-drive RX adds a third electric motor to drive the rear wheels. Total output amounts to 295 horsepower, and it's routed through a specialized continuously variable automatic transmission (CVT).

In Edmunds testing, the 450h went from zero to 60 mph in 7.5 seconds, which is a few tenths of a second slower than the conventionally powered RX 350 and other midsize crossovers.

The upside, though, is that EPA-estimated fuel economy is an impressive 30 mpg combined (32 mpg city/28 mpg highway) with front-wheel drive. The all-wheel-drive version returns 29 mpg combined (30 mpg city/28 mpg highway). Equipped with all-wheel drive and the optional towing hitch, the RX 450h can tow 3,500 pounds.

Every 2014 Lexus RX 450h comes standard with antilock brakes, traction and stability control, front and rear side airbags, side curtain airbags and front knee airbags. Also included is the Safety Connect emergency communications system that includes automatic collision notification, an emergency assist button and stolen vehicle location services.

Optional are parking sensors, a blind-spot monitoring system, a rearview camera and an adaptive cruise control system that includes a pre-collision warning and brake-priming system.

In Edmunds brake testing, the RX 450h came to a stop from 60 mph in 130 feet, which is longer than average for a midsize crossover.

In government crash tests, the RX 450h received four out of five stars for overall crash protection, with four stars for frontal impact protection and five stars for side-impact protection. The Insurance Institute for Highway Safety gave the RX 450h the best possible rating of "Good" in the moderate-overlap frontal-offset, side-impact and roof-strength crash tests. The RX's seat/head restraints also earned a "Good" rating for whiplash protection in rear impacts.

The 2014 Lexus RX 450h's compliant suspension and plentiful sound insulation ably isolate passengers from the outside world and provide excellent comfort on long drives. The hybrid powertrain is also pretty silent. Initial acceleration can seem a little slow unless you really get on the gas, but overall, the 450h feels a lot like its RX 350 sibling. Even when driven briskly through turns, this Lexus hybrid remains composed and secure, though it's not as sporty as many diesel-powered luxury crossover SUVs.

Upscale appointments, exceptional build quality and cutting-edge tech features make the 2014 Lexus RX 450h look and feel suitably expensive for its price. Authentic wood trim and high-quality leather lend an air of opulence, and the optional Mark Levinson sound system is one of the best on the market.

When you opt for the Display Audio or Navigation packages, you get the Lexus Remote Touch system, which is a mouselike device that allows the user to move among a variety of icons on a large centrally located screen. It's a nifty technological achievement, but in practice we've found that the cumbersome on-screen menus and the controller's imprecise nature draw too much of your attention away from the road.

The front seats could use some extra adjustment range, and both thigh and lateral support are somewhat lacking. However, rear passengers will find the seating roomy and comfortable thanks to reclining and sliding adjustments. There's also ample luggage space -- just as much as in the regular RX 350, in fact -- with 40 cubic feet behind the 40/20/40 split-folding rear seats and 80 cubes when they're all lowered. There is no third-row seat available, though.