CNET Car Tech gets a preview of Lexus' updated RX model, the original luxury hybrid SUV.
Wayne CunninghamManaging Editor / Roadshow
Wayne Cunningham reviews cars and writes about automotive technology for CNET's Roadshow. Prior to the automotive beat, he covered spyware, Web building technologies, and computer hardware. He began covering technology and the Web in 1994 as an editor of The Net magazine.
Although the Toyota Prius got all the hybrid hoopla, Lexus showed that a hybrid could be powerful and luxurious with the RX hybrid SUV. That model launched as the RX 400h in 2005, and now gets a much-needed update for the 2010 model year. At Lexus' preview for the car, we got to drive it over mountain roads and spend some serious time trying out the new cabin tech.
The new model is called the RX 450h, as Lexus bumps up the gas engine from 3.3-liters to a 3.5-liter V-6. And, like the original model, that engine is complemented by a full hybrid system, with electric motors that can power the car. With newer battery technology, Lexus was able to make the RX 450h's nickel-metal hydride battery pack, which sits under the rear seat, a little smaller. As with the old version, the gas engine and one motor/generator drive the front wheels. Option it up to all-wheel-drive, and a second motor/generator gets added to power the rear wheels.
We took a sport-trimmed model on a drive over twisty mountain roads in Northern California, and found a lot of improvement. Where the steering on the RX 400h was extremely light, even at speed, Lexus returned the electric-power steering to give more resistance in the RX 450h. Coming through a tight corner at speed, the steering wheel offers much more feedback. The tires were singing in the turns, but the sport-tuned suspension kept the car reasonably flat. Of course, there is a trade-off in that the ride didn't feel as soft as with the RX 400h. Lexus changed the suspension pretty radically in the rear of the RX, taking out the strut towers in favor of a double-wishbone. This new suspension leads to a firmer ride and increases the cargo area.
More power was evident when we pushed the accelerator, as Lexus rates the total system at 295 horsepower in the RX 450h, 27 more horsepower than with the older model. Torque, at 245 pound-feet, is up 37 pound-feet, although that peak torque comes in at 400rpm higher than on the RX 400h. The gas engine now runs on the Atkinson cycle, a method of increasing engine efficiency through valve timing that is currently used on the Toyota Prius and the Mercury Mariner Hybrid. Lexus also fitted the engine with an exhaust recirculation system that keeps the engine warm, making it possible to shut down the engine more frequently and let the electric motors drive the car. Although the power and displacement are increased, these other technologies give the RX 450h 27 mpg for the all-wheel-drive model and 28 mpg for the front-wheel-drive, about 1 mpg better than on the outgoing model.
The actual hybrid behavior felt very similar to the current model. At a stoplight, the engine would shut off. On the green light, our initial, low-speed acceleration was handled by the electric motors until we pushed the pedal enough for the system to kick on the gas engine. The transition felt a little more seamless than on the older car, which could be partly because of Lexus fitting it with more damping materials. According to Lexus, the RX 450h can drive under electric power at speeds up to 10 mph, for approximately two minutes.
Where the old car had a battery mode on its transmission, the new one does away with that in favor of an EV mode button. This mode tries to keep the car running under electric power, but will still kick in the gas engine if needed. Some of these power-train features are borrowed from the high-end Lexus LS 600h sedan. That is true of the transmission, which now has a sport mode and manual selection. As the RX 450h doesn't have any fixed gears, using Toyota/Lexus' unique planetary gearset, sport mode merely lets the engine revs higher, and the manual mode has virtual shift points that really only help for engine braking.
Along with the power-train and suspension updates, Lexus gave the RX 450h a complete and welcome update for the cabin electronics. One of the most notable features is the voice-command system, which can parse sentences for keywords to enact commands. For example, you can say, "I'm cold," and the car will turn up the temperature. Likewise, with the Bluetooth phone system, you can say, "Can you buzz George in his office?" If you have someone named George in your phone book, with an office number, the system will dial that number. Impressively, this system works like Ford Sync, in that you can say the name of someone in your phone book and the car will place the call. But unlike Sync, that type of voice command doesn't work with music.
Along with the voice command, Lexus updated the controller, using a square joystick on the console to control an onscreen cursor. This is the first time we've seen an actual cursor on the screen of a production car, but for anyone that uses a computer (isn't that everyone?), it will be a familiar sight. We like that you can change the settings for the cursor, choosing a different shape and giving more haptic feedback when you move the cursor over a menu item, but the joystick doesn't feel very solid. Worse, it doesn't snap back into its center position when you move it around, which gives it a cheap feeling. Another oddity of this interface is that, when you have a fixed number of icons on the screen, you can still move the cursor all over the place. In a car it seems like it would be better to limit cursor movement to clickable items.
The audio system has the usual sources, but adds USB drive and iPod integration. Strangely, although the navigation system is hard drive-based, you can't rip music to that hard drive, as you can in most cars with this type of navigation. There is a rear-seat DVD option that puts LCDs just behind the headrests of the front seats. Audio is played through a Mark Levinson system that uses 15 speakers to create a surround effect. We tried a variety of music with the system, and found it produced well-controlled bass. You could hear the thump, but it wasn't prone to speaker rattle. The highs could get a little shrill, but they were mostly excellently reproduced. We could hear fairly clear notes through the frequencies, but we didn't get a really hard snap from percussion, as we've heard on other high-end systems.
Besides the power train, the gas only Lexus RX 350 will be comparably equipped to the hybrid Lexus RX 450h. The RX 350 will hit showrooms in the Spring, while the hybrid RX 450h comes around in the early summer.