We like
Outstanding fuel efficiency, lower CO2 emissions than an equivalent diesel, muscular performance, seamless petrol-electric driveline operation, design and build quality, cabin quietness, dynamic improvements, cutting-edge equipment, reduced price premium over petrol RX, value for money, Lexus after-sales service and warranty

Room for improvement
Still not the most dynamic SUV around, disconcerting CVT auto operation, no one-touch indicator function, no third row option, foot-operated parking brake, noisier new V6 requires premium unleaded

THE RX450h isn’t the only hybrid luxury SUV, nor is it the most fuel-efficient hybrid SUV or even the best-performing hybrid SUV.

The latter honours go to US-only oddities like the Mercury Mariner Hybrid, Ford Escape Hybrid, Mazda Tribute Hybrid and Chevrolet Tahoe V8 Hybrid, which can tow up to 2700kg and yet return the city fuel economy of a four-cylinder Camry.

But as the only hybrid SUV on sale in Australia, where the Lexus RX’s key German rivals remain years away from launching a hybrid SUV, the RX450h is all of the above.

Understandably, then, Lexus makes some bold claims about its second-generation petrol-electric RX, which arrives for the first time in three model grades and priced for the first time under $90,000, making it less than $8000 pricier than the equivalent petrol model and about the same price as six-cylinder diesel versions of the BMW X5, Mercedes-Benz ML and Audi Q7.

The fact it produces less exhaust emissions than all of them, as well as smaller four-cylinder luxury SUVs like the X3 and Q5, is only part of the story.

For those that must have the practicality of a wagon body combined with the luxury of a top-shelf sedan and the off-road ability of an all-wheel drive crossover, the RX450h also delivers big-diesel performance with the fuel economy of a four-cylinder petrol vehicle.

While track sessions at Eastern Creek Raceway saw some examples consume more than 25L/100km, overall fuel consumption figures recorded on the undulating launch drive west of Sydney ranged between 7.4L/100km and 9.1L/100km, which is outstanding for an SUV that weighs more than 2.1 tonnes.

Throw in muscular bottom-end performance in the style of a 3.0-litre turbo-diesel and it’s easy to see why Lexus had sold more than 120 examples of the RX450h before it had even arrived.

Of course, the fourth hybrid model from Lexus (as well as the most economical and least expensive) is not perfect.

Its slightly chintzy Japanese styling isn’t for everyone, it continues with a crook foot-operated parking brake, the five-seat-only layout puts it off the menu for those who require three rows of seats, it’s not in the same league as BMW’s X5 in dynamic terms, there’s no handy one-touch indicator function, the 3.5-litre petrol V6 is noisier than the 3.3 it replaces and the CVT auto takes plenty of getting used to.

As with all vehicles fitted with a CVT, burying your right foot in the RX4350h sends the engine immediately towards maximum velocity as the transmission constantly varies its drive ratio to deliver maximum acceleration.

At least, it sounds like peak rpm in place of a conventional tacho there’s a power meter that shows when the engine is either charging (at the blue end of the gauge) or producing maximum power (represented by the red zone).

The new RX hybrid comes with a manual-shift mode, which we expected would act like the override function in a conventional auto, but instead it simply increases the level of engine braking on hand, which at least provides one of the benefits of a manual shifter – but not the most important one.

Get used to the louder V6 operating at high revs when performance is called for, however, and the petrol-electric RX returns effortless acceleration, both from a standing start and for highway overtaking. And leaving for work in the morning in silent electric-only mode (or, as the case may be, arriving home covertly) will be an irresistible party trick.

Other available cutting-technologies include radar-operated adaptive cruise control with crash preparation functions, the Remote Touch Navigation system that’s operated by a computer mouse-like cursor, a useful head-up display and LED headlights.

Wet skidpan tests showed the RX450h had impressive levels of outright cornering grip and that the new stability control system was both seamless and highly effective. Back-to-back tests with the previous RX400h at Eastern Creek showed the upgraded brakes to be far more effective, and the front-biased AWD system was also much kinder to the RX450h’s outside tyres.

Just like the all-new RX released five months ago, the 450h sits flatter in corners thanks to firmer springs and a redesigned rear suspension, and has more direct steering due to a tighter steering ratio – now less than three turns lock-to-lock.

With a degree of jostling readily apparent on bumpy surfaces like corrugations and a hint of steering rattle emerging when hustled, however, the latest Lexus hybrid neither matches the class-leading X5 for body control or handling precision.

The RX’s chief engineer Takayuki Katsuda said the RX was benchmarked against US luxury SUV best-sellers like the Acura (Honda) MDX, as well as the M-class and the X3, X5 and X6, but revealed the Japanese maker had less sporting targets than BMW.

Indeed, brilliant smooth-road ride quality probably remains the most impressive feat of the sharper new RX chassis.

Throw in superb interior noise suppression, first-class design and build quality, an unrivalled level of standard equipment and value for money, a four-year warranty and the top-notch vehicle ergonomics and customer service for which Lexus is famous, and the unbeatable performance-versus-economy equation is simply icing on the RX450h cake.