2010 Lexus RX 450h Hybrid Review – A Little Technology for the Geek in All of Us

By Derek Mau

Pros

• Excellent for around town driving and taking care of all the necessary family functions
• The benefits of a hybrid without sacrificing luxury amenities
• Conservative styling upgrade easily blends in with the thousands of other Lexus RX’s on the road today
• More technology gadgets but with less driver distraction

Cons

• Batteries and electric motors add up to a serious weight penalty with regards to braking and cornering
• Electronic steering control is good for mothers on their way to PTA meetings, but not so good for relaying feedback from the road
• Horrific blind spot
• No towing capacity

The new generation Lexus RX blends the geekiness of high technology with the green consciousness of driving a hybrid car. Launched in the summer of 2009 as a successor to the RX 400h, Lexus’ new RX 450h builds on the success of the company’s first luxury hybrid SUV. Visually similar to the RX 350, the 450h has a few of its own unique styling features, including an exclusive grille, hybrid badging with blue-trimmed Lexus logos, unique front bumper, special 19-inch wheels, blue-tinted headlamps and taillamps, and optional LED headlamps.

Exterior Styling

Toyota played it safe with the Lexus styling. You have to look really close to catch the differences between the new and previous generation RX hybrid. The RX 450h is less rounded and bubbly than its predecessor. It’s also a bit wider and seems to sit lower on the road, but that’s just because of its headlight placement and hood sculpting. From the front, the RX 450h looks bolder and stronger, but still elegant.

The RX 450h’s profile is similar to the RX 400h’s. The roof-mounted spoiler is a bit stronger and hides the rear wiper, and Lexus has added a small “shark-fin” antenna. The door handles are now body-colored, but there’s new chrome trim around the windows and along the door bottoms. There’s also a discreet hybrid badge that sits near the lower chrome strip.

Beneath the Sheetmetal

The 2010 Lexus RX 450h enhances its luxury ride and cabin with a hybrid power train that achieves fuel economy unheard of for an SUV. The hybrid-specific, 2GR-FXE version of the 3.5-liter V6 resembles the revised V6 featured in the 2010 Lexus RX 350, but it has higher compression (12.5:1 instead of 10.8:1) and runs on the fuel-saving Atkinson cycle. Additionally, its variable valve timing operates only on the intake side.

The Atkinson cycle keeps the intake valves open during part of the compression stroke, so this V6 makes just 245 horsepower at 6,000 rpm and 234 pound-feet of torque at 4,800 rpm, while the conventional version of this V6 delivers 275 hp and 257 lb-ft of torque. In short, this is a significant increase over the 3.3-liter V6′s 208 hp and 212 lb-ft of torque.

The RX 450h also draws power from its 37-kilowatt, nickel-metal hydride battery pack to power the h-model’s electric motors (a 123-kW electric motor for the front-wheel-drive RX and an additional rear 50-kW motor for the all-wheel-drive RX). The battery pack provides 50 hp, giving the 2010 Lexus RX 450h a rating of 295 hp total, up from the 268 hp of the RX 400h. In operation, there is an almost seamless transition between the electric motors and ICE. Perhaps this is the result of the two-stage mechanism to absorb torque that the Lexus engineers have added to the transaxle’s flywheel damper.

We noticed that the battery pack is rated for fewer kilowatts in the RX 450h; the RX 400h’s battery pack had a 45-kW rating. Don’t let the numbers mislead you. The 2010 RX 450h actually gets more power out of its battery pack due to an improved cooling system for the inverter and converters — it’s the same setup used on the Lexus LS 600h L.

Total power from engine and electric motor is rated at 295 horsepower, a little short of a V-8, while fuel economy gets an EPA-rated 32 mpg city and 28 mpg highway. Our ballistic driving style netted us 28 mpg overall, a figure that many four cylinder cars would have trouble hitting.

Driving Impressions

Acceleration was peppy for a hybrid SUV vehicle weighing nearly 4800 pounds and there was little trouble accelerating up to high speeds on the highway, thanks to the capable V6 engine.  Likewise braking was responsive, though it had a strangely different feel thanks to the regenerative braking features.

The crossover also features a new, uniquely designed double-wishbone rear suspension that helps provide exceptional agility and control. Its distinctive design also allows for five percent more cargo volume and easier loading. To complement the new rear suspension and provide excellent dexterity and ride comfort, the front McPherson strut geometry was optimized. The suspension did take turns very well, but the trade-off was that it just did not perform sufficiently when absorbing large road bumps.

As for the feel of the vehicle, its very comfortable and spacious.  The steering wheel retracts when you’re not driving, a nice touch.  The drive is relatively smooth and NVH (noise, vibration, and harshness) is not overly high, thanks in part to the smooth electric motors.

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