2006 Lexus RX 400hPosted on October 20th, 2005
Eight Cylinder Power from a V6 Hybrid
By Nina Russin
The all-wheel drive Lexus RX 400h is based on the manufacturer’s best-selling RX 330 platform. The RX 400h sport-utility vehicle is Lexus’ first hybrid: it utilizes the same power train technology as the Toyota Prius.
However, unlike the Prius, Lexus engineers focused on power and performance. The “400h” designation indicates that the V6 gas engine (the same block used in the RX 330) and three electric motors generate power equivalent an eight cylinder engine.
Peak power is eighty percent higher than the Prius. At the same time, the Lexus RX 400h averages 28 miles-per-gallon in combined city and highway driving: fuel economy comparable to the industry average for gas-powered compact sedans.
Full Hybrid Technology
Like the Prius, the Lexus RX 400h is a full hybrid: it can run on electrical power alone while idling, and at low speeds. The gas engine kicks in during hard acceleration, high-speed cruising, or when the air conditioner (on maximum setting) places an additional load on the engine.
Because the Lexus sport-utility vehicle is all-wheel drive, it has electric motors on both front and rear axles. A third electric motor distributes power to the drive wheels according to the road conditions.
The hybrid engine is mated to a continuously variable transmission, so there is no “shift shock” between gears. Rather than selecting a low gear to slow down the engine, the driver engages a “B” setting on the gear shift lever, that applies a small amount of braking. Energy generated during braking is used to recharge the nickel metal hydride batter pack, located under the vehicle’s rear seat.
A Real-World Solution to Limited Resources
The nice thing about driving hybrids is that they share many of the advantages of alternative fuel vehicles such as pure electric cars, natural gas and hydrogen, without the disadvantages.
Unlike electric cars, a hybrid recharges automatically during vehicle operation. And unlike natural gas and hydrogen, it operates on the same fuel as traditional gas-powered cars: just a lot less of it.
A new sealed gas tank design reduces the amount of fuel that evaporates into the air for refueling and reduces harmful emissions. Other gas-saving technology includes drive and brake-by-wire systems, which reduce eliminate energy loss from mechanical linkages and internal friction.
The driving experience itself is quite similar to gas-powered cars, except that the engine shuts off when power isn’t needed, and the car tends to accelerate harder from a stop. That’s because electric motors develop most of their peak torque at very low speeds.
The Lexus RX 400h accelerates from zero to sixty miles per hour in 7.3 seconds, according to the manufacturer’s internal tests. Thirty-to-fifty mile per hour acceleration is 3.4 seconds, making merging into high speed traffic a non-issue. There are two power meters on the instrument panel that illustrate the gas-electric power distribution: one in the driver’s side gauge cluster, and a second display that is integrated into the navigation system.
The front-to-rear weight balance in the Lexus RX 400h is slightly different than in the RX 330, due to the weight of the battery pack in the rear. Engineers have used slightly different suspension tuning to adjust for the difference.
Lexus held its press preview for the RX 400h on the Big Island of Hawaii. Because the RX 400h is not intended for serious off-road driving, the drive routes were on paved roads only, although some of the narrower two-lane routes were as bumpy as graded dirt. Driving routes passed through some hilly areas, with elevations up to 3,000 feet.
As with all Lexuses, the RX 400h does an exceptional job of isolating the driver and passengers from road noise and vibration. It accelerates powerfully and seamlessly up hills: so powerfully in fact that it’s easy to lose track of the speedometer readings. The vehicle also acts a little more nose-heavy than the RX 330. Even with the B setting engaged, it slides down the hill at a good clip.
The suspension does a good job of keeping the sport-utility flat during cornering, even when taking the corners at speed. The transition from pure electric to electric and gas power is barely noticeable.
The interior of the RX 400h is well designed from an ergonomic stance. The seats, including standard 10-way power driver’s seat and eight-way power front passenger seat, provide good lower back support.
The center console has two cupholders, we well as a small cubby for holding a cell phone and a larger one for CDs. The large locking glove box is a useful feature for those who want to secure valuables at the trail head. There is a 12-volt power outlet integrated into a storage bin at the front of the center console, and a 110-volt power outlet in the cargo area.
The second-row seats feature a 20/20/40 split design. They fold flat without removing the headrests to create a load floor large enough to hold a couple of road bikes with the front wheels off.
A power rear liftgate makes it easier to load cargo into the rear without having to struggle with the latch. Tools for the spare tire are located under the cargo floor. There is also a standard first aid kit. The RX 400h tows up to 3,500 pounds: the minimum for our active lifestyle vehicle criteria.
The first models that roll into Lexus dealerships this April come in one trim level only. The full-loaded version has a MSRP of $48,535. In comparison, pricing for the all-wheel drive version of the RX330 begins at about $37,000. Therefore, the cost-benefit of fuel savings is not a good reason for buying the Lexus hybrid.
But for those who are willing and able to pay the premium, the RX 400h is an appealing package. Standard equipment includes a navigation system with a backup camera (similar to the one available in the Toyota Sienna minivan), a roof rack and rails, first aid kit, high intensity discharge headlamps with an adaptive feature that moves with the steering gear, power, tilt and telescopic steering wheel, moon roof, six disc CD changer and more.
A new dynamic stability system anticipates vehicle instability in almost any direction and automatically adjusts for it. The Lexus RX 400h also comes standard with antilock braking and traction control. It rides on special 18-inch wheels and tires.
Standard passive safety features include front, side, side curtain and a driver’s side knee airbag. Rain sensing wipers improve forward visibility in bad weather. The windshield and side windows are made of a water-repellant glass that causes rain to bead up.
The standard adaptive front headlamps turn in the direction of the steering wheel to better illuminate corners on dark, two-lane roads. Redundant audio, speedometer and trip meter controls on the steering wheel reduce the amount of time the driver’s eyes are off the road.
The Lexus RX 400h is one of two hybrid sport-utility vehicles that Toyota is introducing this year. A hybrid version of the Highlander that will be available in both two- and four-wheel drive follows later.
Fuel economy on the Lexus RX 400h averages 31 miles per gallon in the city and 27 on the highway. The slightly better city figures reflect the use of electric power alone during certain driving situations.
The Lexus RX 400h comes with the standard Lexus 48 month/50,000 mile basic warranty that includes free roadside assistance for the warranty period. The hybrid-related components are covered for eight years or 100,000 miles.
Price as tested: $48,535
Horsepower: 208 @ 5600 rpm
Torque: 212 lbs.-ft. @ 4400 rpm
0 to 60: 7.3 seconds
Antilock brakes: Standard
Side curtain airbags: Standard
First aid kit: Yes
Bicycle friendly: Yes
Fuel economy: 31/27 city/highway
Comments: The Lexus RX 400h goes on sale April 15.
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