Review: 2010 Lexus RX450h is the pinnacle of autonomous fuel-sippers

With a slew of sensors and CPUs, the 2010 Lexus RX450h can pretty much drive itself. Want to go somewhere? Sit down in the driver's seat, use the Remote Touch device (a.k.a. "mouse") to tell the crossover where you want to go, and follow the easy-as-store-bought-pie instructions to your destination. Whether or not this is a good thing depends on how badly you want to feel like you're in control of your commute. For those concerned about fuel economy and comfort, the almost-autonomous nature of the RX450h is nice, but certainly doesn't offer a tremendous amount of ability to control how much fuel you burn moving down the street. As it turns out, this is a feature, not a bug. Find out why after the jump.

Photos by Sebastian Blanco / Copyright ©2009 Weblogs, Inc.

How does the RX450h make it absurdly easy to get from one point to another? Through a combination of shiny luxuries and thoughtful technologies that give the operator fewer things to concentrate on while driving. Front and center among these new technologies is the car's heads-up display (HUD), which integrates directions from the navigation system in an amazingly intuitive way. Of course, to see those HUD arrows, you need to have the navigation system, which adds at least $2,550 to the RX450h's $41,660 base price.

Whether or not you opt to spend the extra money, the HUD exemplifies how Lexus has made the RX450h a simple and comfortable hybrid. Aside from directions, it displays your speed, along with the ability to adjust the brightness and angle to provide exactly the right look no matter the conditions (it can also be turned off). During long drives, when it comes time to lean forward on the steering wheel to straighten up the back for a few moments, you can still see how fast you're going, something we truly appreciated after a few hours on the highway. Of course, if you're letting the RX450h control its own speed with its adaptive cruise control, knowing your mph doesn't matter as much, but still, it's a nice touch.




We drove just over 550 miles during our week with this all-wheel drive 2010 Lexus 450h. For the first 250 or so miles, we let the machine do its thing in Eco mode: the adaptive cruise control was on and set to just a hair over the speed limit, climate control was set to auto and we followed the navigation system where it told us to go. The distance that the adaptive cruise control sets between the RX450h and the vehicle in front of it is, of course, adjustable. Nonetheless, it's not suitable for drafting – which we don't endorse anyway – and on the closest setting, it still kept us a safe distance away from other vehicles, even when people shifted lanes directly in front of us.

On auto-pilot (or as close as it gets these days), the RX450h automatically achieved 28.6 mpg – nearly in line with the EPA's 28/30 mpg estimates for the all-wheel-drive model (the front-wheel drive variant clocks in at 32/28). On the second half of our journey, we tried to beat the vehicle's full-auto performance. We turned off the air and (why not) also the auto-dimming (electrochromatic) rearview mirror system and told the CUV when and how hard to accelerate by using the pedals instead of the cruise control. We also tried our hand at manually shifting the gears of the Electronically Controlled Continuously Variable Transmission (ECVT). Embarrassingly but perhaps predictably, all of this produced poorer fuel economy than the automagic system. Over the entire week, we managed 27.6 mpg. Score one for letting this particular vehicle drive you.



The RX450h strives to offer as much comfort as possible, so it's packed with luxury touches like side mirror glass that rotate downward when you put it into reverse for curb-finding and friendly interior lights that come on when you approach the car with the wireless key fob in the dark (neither of which is a new feature, but very convenient). The lights remind you that, hey, this car wants you to feel at ease. Quite a bit poorer in the wallet, but at ease nonetheless.

On the road, the smoothness of the RX's ride cannot be overstated. Even though we happened to be driving a pre-production model, everything was as smooth as melty mayonnaise. This is Lexus' second-generation RX hybrid (following the RX400h), and minor improvements can be felt all around. The hybrid powertrain shuts off the 3.5-liter V-6 engine nicely at stoplights; it comes back on without any hassle when it's time to move again. If you're inclined to use the 37 kWh nickel-metal hydride battery to its fullest extent, the RX450h does have an EV mode that will allow the car to go up to 10 mph for about two minutes. As in the 2010 Toyota Prius, EV mode is a limited tease of what a real electric car can offer, but it's better than nothing, and ideal for teenagers trying to sneak in to their parents driveways after curfew. Eco mode, which we used extensively during out week-long test, automatically controls the air conditioning and throttle inputs for increased efficiency.



To keep track of what's going on with the hybrid RX, there is a Multi-Information Display between the speedometer and the green driving gauge. This screen can toggle between all sorts of information readouts: average speed, tire pressure, average mpg, whether or not the vehicle is in EV or Eco mode and more. Switching the information type is controlled by a lever on the steering wheel, which is also used to engage EV or Eco mode and other options.

The green driving gauge isn't nearly as easy to use as similar displays in the Prius or the Ford Fusion Hybrid, but does provide a way to tell if you're charging the batteries from the brakes or pushing down on the gas pedal enough to enter the "Power" zone. We avoided this zone as much as possible – it means you're accelerating quickly – in our effort to get a decent mpg result. When we did need to use it, the RX450h's penchant for smoothness remained at our fingertips.



In the end, if you're seated in the comfortable seats of the RX450h and apply just a modicum of awareness and effort, you're in a crossover that will take you where you want to go, no questions asked. Compared to the non-hybrid RX350, the RX450h gets an official fuel economy improvement of around nine mpg. Toyota hasn't kept it a secret that it wants the fuel sippers to gravitate towards the Prius, while Lexus' hybrid line is more about adding creature comforts than it is about significantly reducing the amount of fuel one burns. Having said that, we applaud the mpg improvement to date, particularly for a vehicle of its size.

Still, does it make sense to spend $5,000 or so more for the RX450h than the RX350? You're undoubtedly getting some fuel economy benefits from the hybrid powertrain, but five grand worth? There's a simple way to answer this question: ask the car. Remember, the RX450h doesn't want you to think, it doesn't beg you to be involved with the driving experience, it just wants you to feel comfortable. If the hybrid badge and better mpg warms your cockles, then go for it.

Photos by Sebastian Blanco / Copyright ©2009 Weblogs, Inc.