The Lexus RX 350 is smooth in just about any situation. It travels over rough, broken, pavement without jostling whoever is inside, but it does not float. Its fully independent suspension is well damped, helping keep the tires pressed to the pavement, so the driver feels confidant that the RX will respond properly to quick turns on the steering wheel. The steering is light and accurate and the RX feels poised when cornering.
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 with City mileage that exceeds Highway. With the RX 400h, it's because the vehicle can run strictly on electric power at lower city speeds, using energy generated in several ways (including the gas engine) and stored in its batteries.
On the downside, the RX 400h drones under light throttle and the sound it makes under acceleration is not entirely pleasing, either. In some test vehicles we could feel the gas V6 kick on and off, and it's a lurch you won't feel in other Lexus products. Also, there's a little torque steer, or at least something that feels like torque steer: Pull up to a stop sign, stand on the gas and make a right turn, and you'll feel a slight tug on the steering wheel or a resistance to turning. The brakes may be the most un-Lexus-like component of the RX 400h. They stop the car with authority, no worries there. But they sometimes feel uneven, as the regenerative effect of the electric motors helped slow the car, which makes it more challenging to modulate the pedal for smooth stops, particularly at parking lot speeds.
The RX 350's brakes are smooth and respond with good pedal feel in all circumstances. Its brakes are relatively large and the anti-lock braking system is well tuned, helping a driver maintain steering control during emergency stops. The system features Electronic Brake-force Distribution, which directs braking effort in proportion to weight bias and brake loading for improved stability under hard braking, and Brake Assist, which is designed to sense panic braking and to maintain full braking pressure, even if the driver makes the common mistake of relaxing pressure on the brake pedal.
Both models have Vehicle Stability Control, which helps the driver stay on the intended path on slippery surfaces. New for 2008, a cut-off switch allows the driver to turn off the stability and traction control functions.
The handling of the RX 400h is a bit more responsive and it feels sportier than the RX 350 without the Performance Package. The 400h suspension is firmer, and it corners with less lean. Its optional 18-inch wheels come fitted with stickier tires.
All Lexus RX models are nearly immune to road noise, even with the large greenhouse and expansive glass, and there's very little wind noise. Lexus engineers took the time to aerodynamically shape the roof rack for quieter running.
The all-wheel-drive system on models so equipped automatically routes power to the wheels with the best grip and works with the ABS to slow any wheel that slips and spins. The RX 350 is not a serious off-road vehicle, as it has no under-body armor, low-range or locking differentials. Yet if you tread lightly, it's fine for unpaved roads.
An RX 400h driver should stick to pavement, or risk damaging the hybrid drivetrain. But with all-wheel drive either vehicle is great for the Snow Belt. Deep snow or packed snow (with the right tires) and slippery surfaces are no problem. The all-wheel-drive models find whatever grip is available and add driving confidence in bad weather.
The optional Performance Package for the RX 350 features an air suspension with four driver-selectable settings. The air suspension automatically lowers the vehicle by 0.3 inches at speeds higher than 62 mph, to reduce drag for better handling and fuel economy. Drivers can select a mode that lowers the car by 0.6 inches for better cornering and a smoother ride. Rough roads and unpaved trails requiring greater ground clearance can be accommodated by the High position, which raises the ride height by 1.2 inches at speeds up to 30 mph. An Access mode lowers the RX 330 for easier entry and exit when in Park. The Access mode can be programmed to lower the RX automatically when the ignition is turned off, a nice feature.
