The RX 350 offers brisk acceleration performance to its powerful yet efficient 3.5-liter V6 engine introduced on 2007 models.The RX 400h features a hybrid gas-electric powerplant.

For 2008, the changes are mainly cosmetic.The only mechanical change is the addition of a Vehicle Stability Control cut-off switch.

The 2008 Lexus RX 350 features a new front grille design and chrome door handles.Two new exterior colors are available as well as a new interior wood trim option, black bird's-eye maple, available with the light-gray interior.Newly optional are seven-spoke, 18-inch alloy wheels with a liquid graphite finish.

The 2008 Lexus RX 400h gets a new finish on the grille, a blue hybrid badge on the front of models without the towing package, chrome door handles, new finish for the five-spoke, 18-inch wheels, a color-keyed rear spoiler, seven new colors, and black bird's-eye maple wood trim is available with light-gray interiors.

With the RX series, Lexus pioneered the crossover-style SUV, based on a unit-body car platform rather than a heavy-duty truck frame.Crossover utility vehicles offer better ride and handling and better fuel economy than truck-based SUVs, but they still deliver many of the things buyers want in an SUV: more cargo space than a car, a better view over traffic and a sense of security that accompanies an elevated driving position.The RX doesn't offer the big towing capacity or off-road capability of a true truck, but an all-wheel-drive RX 350 handles gravel and snow with ease, and it can tow up to 3500 pounds with the optional trailer package.

The RX is as quiet inside as most cars.It's easy to drive and easier than most SUVs to park, with light steering and responsive brakes.It also offers the latest technology: headlights that swivel to help the driver see around corners, a rear-mounted camera that displays what's behind on the dash-mounted navigation screen, a voice-activated hands-free telephone system, cruise control that can adjust for changes in traffic and a giant sunroof.It's equipped with the latest in passive safety features, including seven airbags.

The RX 400h combines a gasoline-powered V6 with one high-torque electric motor-generator on the front-wheel-drive model, and two motors on the all-wheel-drive model.The gas engine can propel the car or recharge the batteries.Most of the time the RX 400h runs on a combination of the V6 and electric motors, but in certain situations it will run strictly on the V6 engine, and in others strictly with the electric motors.

Emissions are extremely low, reducing the impact on the environment to something in the neighborhood of nil.The RX 400h burns about as much gas as a compact car.Yet it drives essentially the same as the RX 350.It accelerates as quickly off the line (which is quite quick), and more quickly at certain speeds.The main difference comes when the RX 400h runs only on the electric motors: when it glides serenely through a parking lot or down a neighborhood street.

In short, the RX 400h delivers the performance of some V8-powered SUVs with the economy of a four-cylinder.There are lots of good reasons to choose it over the standard RX 350, but not economic reasons.The RX 350 is a very efficient vehicle in its own right, and now that Lexus has equipped both variants identically, the $4,000 price premium for the RX 400h pays strictly for the hybrid drivetrain.

The Lexus RX 350 is well-suited for just about any assignment, from a drive along the Pacific Coast Highway to a camping trip in the Sierra Nevada.It's stylish and at home in the valet line at a fancy restaurant.

Standard features: cloth upholstery, automatic dual-zone climate control, a 132-watt AM/FM/cassette stereo with eight-speakers and an in-dash, six-CD changer, cruise control, privacy glass, automatic headlamps, 10-way power adjustment for both front seats, 17-inch aluminum wheels and leather trim for the steering wheel and shift knob.

Options for both the RX 350 and RX 400h: The Premium Package ($1,245) includes leather upholstery, power tilt/telescope steering wheel, a roof rack, power moonroof and entry lights that illuminate the ground below the doors.The Premium Plus Package ($2,060) includes the features from the Premium Package and adds high-intensity discharge headlamps that turn in the direction of travel.

The navigation system ($2,650) with Bluetooth and voice command capability includes a rear-view camera that projects an image of what's behind whenever reverse is engaged.

The navigation system with Mark Levinson audio ($6,190) on the RX 350 starts with the Premium Plus Package and adds 210 watts, more speakers with a subwoofer and high-tech digital sound processing.On the RX 400h, it costs less ($4,130) but requires purchasing either the Premium or Premium Plus Package.The Mark Levinson audio system is available as a stand-alone option on the RX 400h ($980).

A heated-seat package ($665) comes with rain-sensing wipers and headlight washers.The Tow Prep ($160) package includes a transmission cooler, heavy-duty alternator and larger radiator.Other options include a rear-seat DVD entertainment system ($1,740 for the RX 350; $1,840 for the RX 400h), laser-managed Dynamic Cruise Control ($600), and HID headlamps ($815).XM and Sirius satellite radio are offered as a dealer-installed option.

A few options are available on only the RX 350: The giant multi-panel sunroof ($2,840) comes packaged with features from the Premium Package.The Performance Package ($4,055) includes all of the items in the Premium PLUS Package, plus 18-inch graphite-colored aluminum alloy wheels with wider tires, height-adjustable air suspension, sequential-shifting transmission, and rain-sensing wipers.Heated front seats ($540) can be ordered as a stand-alone option.

Safety features that come standard include the mandated front airbags, plus a smaller airbag to protect the driver's knees.Front passengers get side-impact airbags for torso protection, while the curtain-style head protection airbags span both rows and deploy to offer head protection if the vehicle senses the possibility of a rollover.Advanced ABS, traction control and electronic stability control come standard.

The current Lexus RX models build on the style set by the original RX 300.Its shape is defined by radically raked, body-colored pillars at the four corners of the cabin, with window frames blacked out to blend into the ovoid shape of the side windows.

The raked-back front fascia and headlamps are reminiscent of the Lexus ES 330 sedan, and the optional, gem-like high-intensity discharge headlights look like they mean business.The headlights also feature an Adaptive Front Lighting System, which uses an on-board processor to calculate the optimum angle to illuminate a turn then swivels the headlamp closest to the turn accordingly, allowing the driver to see better around corners.

The beefy front bumper and pronounced fender flares are designed to suggest the rugged, off-pavement expected in an SUV.Its door handles are of the reach-through type, which are generally more hand-friendly than the fingertip pull-up type, with less opportunity to break long fingernails or snap away from your fingers when you're in a hurry.

Viewed from the rear, the RX reveals a visor-like spoiler over the top edge of its rear window, a short radio antenna at the right-rear corner of the roof (promising better reception in marginal areas than the also-included imbedded-in-glass type), and clear-lens tail lights.

Subtle styling differences distinguish the RX 400h from the RX 350.Among them: a front bumper and grille designed to allow more air into the RX 400h engine bay for more cooling and tail lamps with LEDs instead of traditional incandescent bulbs.

For 2008, there are a few tweaks to the appearance of both models, with a new front grille design for the RX 350, a new grille finish for the 400h, and chrome door handles on both.The 400h models without a towing package sport a blue hybrid badge on the front, and the rear spoiler is color-keyed.

The RX 400h is also available with the 18-inch wheels and tires offered on the RX 350, and it says something about the thinking behind the hybrid.Lexus could have used hard, low-grip tires that reduce rolling resistance and further improve fuel economy, but chose to enhance handling instead.

The 400h hybrid powertrain adds less than 300 pounds to the curb weight and that's an impressive engineering achievement, given the powerful motors and batteries.They're all placed low in the vehicle, so they don't substantially raise the center of gravity or affect handling.While the hybrid does give up two gallons of fuel capacity, its 17.2-gallon tank is still larger than that in most vehicles, and it loses none of the 84.7 cubic feet of cargo space available in the RX 350.

The RX 350 has splashes of walnut or bird's eye maple on the doors and center console and on its steering wheel.The RX 400h has brushed aluminum that resembles the metallic plastic used in both models around the gauges and switch plates and its steering wheel is wrapped completely in leather.For 2008, black bird's-eye maple wood trim is available with light-gray interiors on either model.

Getting into the Lexus RX is easy, with no need to climb up or duck down.The front seats are positioned off the floor at a comfortable chair height and are snug and supportive.The seat bottoms are relatively flat, making it easy to slide in and out.Folding armrests on both front seats offer more comfort on longer trips.The center console slides forward and back, allowing room for a purse or whatever else you might stow between the front seats.

The instrument cluster in the RX 350 features three large, round gauges trimmed in silver, with legible script and near-perfect backlighting.In the RX 400h, an illuminated meter replaces the traditional tachometer on the left, displaying the level of power generated by the hybrid powertrain.The driver can also monitor gas-electric power distribution on the multi-function display, which dominates the center stack and serves as the navigation screen in vehicles so equipped.

This seven-inch screen is also used for climate control and trip computer functions, and can display the outside temperature and clock (with alarm).It shows the image provided by the back-up camera, which is included with the navigation system and automatically activates when the transmission is shifted into reverse.You can't drive backward by watching the screen, but it's very useful for checking for low obstacles (and people) that would be difficult to see just by looking over the shoulder, and it also helps when backing the RX into a parking space.

The optional navigation system is one of the best.The current Lexus package includes voice activation, Bluetooth interface with compatible cellular phones and impressive shadowed graphics.There's a downside to many of these new, integrated control systems, to be sure, and the RX is no different.You have to press two buttons to change the fan speed, for example, rather than just one.Lexus dealers can program the default settings of many of the control functions, so be sure you have them tailor automatic door locking and other features to your preferences.If you're fighting some feature, it can probably be programmed to operate differently.

Overall, we find the switches and controls in the RX (and in Lexus cars generally) to be among the best.They're well placed, properly sized and soft to the touch, yet firm and positive in movement.

However, there are exceptions to this: The trip odometer can be hard to read.Perhaps more annoying, the switch that moves the outside mirrors is positioned such that, when drivers get the seat positioned in a comfortable position, many can't reach the mirror switch without leaning forward in the seat.Thus, they have to lean, adjust the mirrors and then lean back to check the mirrors from the position they'll take while driving.This trial-and-error process reminds us of old sports cars or trucks where you get out of the car, adjust the mirror, get out of the car, readjust the mirror.And in one of our test cars, the electric steering column moved in un-Lexus-like skips and lurches, rather than with a nice, smooth motion.

Audio controls in the RX are low on the center stack.The radio has big knobs for volume and tuning that are easy to use without distraction from the task of driving.The standard audio system sounds great, with 132 watts of output, eight-speakers and a CD-changer.We like that Lexus still includes a cassette for o.

The 3.5-liter V6 takes the RX beyond snappy to a feeling of real power without sacrificing the trademark smoothness.Indeed, this V6 is so powerful that it responds aggressively, even abruptly, to anything more than a bit of gas.It takes a bit of practice to adjust to the throttle response.The aluminum V6 features the latest control technology, including Lexus's Variable Valve Timing with Intelligence system (VVT-i), which balances high-rev horsepower with good torque at all engine speeds and low emissions.

The five-speed automatic makes good use of the power from the RX 350's engine.It quickly kicks down a gear or two when the driver dips the accelerator, and holds that gear all the way to the redline when the pedal is floored, before shifting up smoothly and smartly.With more gears than a traditional four-speed automatic, the five-speed keeps the engine purring in the fat part of the power band.A low first gear offers quicker response off the line, useful when you need to merge into traffic from a standing start.Fifth gear, meanwhile, provides lower engine speeds when cruising, which translates into less engine noise and better gas mileage.

In terms of acceleration performance, the RX 350 and RX 400h are closely matched.The RX 350 can accelerate from 0 to 60 mph in 7.3 seconds with front-wheel drive, or 7.4 seconds with all-wheel drive.The RX 400h does 0-60 in 7.5 seconds with front-wheel drive, 7.3 seconds for all-wheel drive.

Driving the RX 400h isn't a lot different than driving the RX 350.It's smooth and responsive, yet there are some obvious distinctions apparent the moment it starts up.Twist the key and the dash lights up but there's no sound of an engine starting, only silence.Slide the transmission lever to drive and you can pull silently away on electric power.This is not intuitive because we're all accustomed to hearing and feeling an engine running before shifting into drive.Shifting into drive without sound or vibration can feel strange.You get used to it, though, and we enjoy running in electric-only mode.

At low speeds, the RX 400h is perfectly content to operate in electric-only mode.It's quiet, and you begin to hear things that are normally drowned out by an engine.We found this interesting and enjoyable.It will run in this silent mode in stop-and-go commuter traffic, eliminating the noise and pollution that the cars around you are putting out.The RX 400h maneuvers silently through crowded parking lots as well, where pedestrians often will not hear you coming and therefore won't always get out of the way.You learn to be patient and need to exercise extra care.Toyota's hybrid system is an electric motor assisted by a gas engine, while some of the other hybrid systems are oriented around a gasoline engine assisted by an electric motor.

The front-wheel-drive version features a single electric motor in front; the all-wheel-drive model uses one motor in front and one in the rear.The V6 engine starts whenever it's needed to supplement the electric motor.Step hard on the gas pedal and the V6 will usually kick in quickly and seamlessly.In all cases the response is immediate acceleration, and plenty of it.The 400h is impressively quick, particularly when overtaking a slower vehicle between 30 and 60 mph.

The RX 400h enjoys a 10 mpg edge in fuel efficiency over the RX 350 in the EPA's City cycle, earning 28/25 mpg City/Highway with front-wheel drive.That might look odd at first, as we rarely see EPA ratings wi.

John Matras filed the original report from Pennsylvania, with staff reports by NewCarTestDrive.com.