Lexus RX 400h 2007 Review

Road Test

Overall rating: 3.0/5.0
Engine/Drivetrain/Chassis: 3.0/5.0
Price, Packaging and Practicality: 3.0/5.0
Safety: 4.0/5.0
Behind the wheel: 2.5/5.0
X-factor: 3.5/5.0

Few new automotive technologies have received the sort of media attention and widespread public awareness as petrol/electric hybrids. On one hand it's surprising really -- there are, after all, just four hybrid models on sale in Australia. On the other hand, never underestimate the market muscle of the Big T...

Yep, of the quartet of these "environmentally friendly" vehicles on sale Down Under, three are from the Toyota Motor Corporation camp. Toyota's own Prius needs little introduction, meantime Lexus, in particular, has been using the hybrid factor as its great point of difference.

Indeed in a relatively small line-up, the premium marque currently boasts the GS450h executive saloon and the subject of this review, the RX400h SUV. For the record, Lexus' new range-topper, the LS600h limo, is also a hybrid -- it goes on sale in October.

The RX is the first hybrid SUV to launch in Australia and as an all-wheel drive, it sports the most sophisticated hybrid technology to date. Drive comes courtesy of three separate sources -- a 155kW/288Nm 3.3-litre V6 petrol engine, a 123kW/333Nm front electric motor and 50kW/130Nm rear electric motor. Despite the maths, Toyota says this adds up a total maximum power output of 200kW.

Like its petrol-only kin (RX350), the RX400h is essentially a front-driver until the car's electronics determine wheel slip. Then the rear electric motor kicks in to offer drive from the rear wheels.

The 400h is a reasonably stylish SUV with more car-like than truck-like lines. Inside you won't notice that you are in a hybrid until you turn the key, for in addition to the usual array of satnav, audio and climate control functions accessible via the centrally mounted touch screen, there's also a comprehensive graphic that (like the Prius) features electric motor, battery and petrol engine diagrams that tell you exactly where the power and torque are coming and going at all times.

The bulk of the 400h's standard equipment is shared with the $10,000 cheaper Sports Luxury RX350 and includes climate control aircon, power windows, mirrors, front seats and moonroof, full leather trim, 18-inch alloys, rear-view camera and parking sensors, satnav and an 11-speaker Mark Levinson six-stack CD audio system.

As is the Lexus tradition, comfort is a big factor with big plush leather trimmed seats providing plenty of cushioning and a reasonable degree of support. Then there are the trademark low levels of NVH -- you don't get any quieter on start up than the RX400h.

The reason, of course, is because 'starting' doesn't kick the V6 into life but rather turns on the electrical drive system. Turn the key, slip the transmission lever into drive and press the accelerator pedal and the car silently moves away from rest under electric power. Give the throttle a decent shove, however, and it only takes a moment before all three powerplants join forces to get you off and away from standstill at a reasonably enthusiastic rate -- though still in a very smooth and refined manner.

Lexus claims a 0-100km/h time of 8.4sec for the 400h. By way of comparison, the RX350 takes 8.4sec and a turbodiesel like, say, VW's V6 TDI Touareg takes 9.2sec.

Only when the petrol engine is revving hard (although at what speed remains a mystery, as there is no tacho) and the CVT transmission are being pushed along does the drivetrain start to get a bit noisy -- though probably no more than the RX350 under similar duress.

Hybrids' raison d'etre is to improve fuel economy (and therefore reduce emissions). While Lexus claims an ADR 81/01 combined test figure of 8.1lt/100km, we managed an average of just 10.3lt/100km -- getting about 490km out of the 65-litre tank. Nearly half of this distance was country cruising at highway speeds when the fuel consumption rose to about 10.8lt/100km. The lower average highlights the hybrid system's strength as a low-speed urban commuter.

While the overall figures are not astonishing (and certainly easily matched by turbodiesel competitors -- using the above examples VW's TDI uses 10.9lt/100km and the RX350 petrol 11.2lt) it is still a fairly good result for an SUV-style vehicle that weighs in at just over two tonnes.

What you also get, alas, is a fairly ordinary drive experience. As mentioned before, the priority in the RX is on comfort and there is no doubt that there is plenty of suppleness to soft-ish suspension. This results in barely a ripple being felt through the seats or inside the cabin over most surfaces.

Head off onto a twisting country road, however, and the car feels cumbersome with anything more than moderate cornering speed inducing a fair degree of body roll which, when combined with the flat and slippery leather-clad seats, means you have to have a firm grip on the steering wheel to maintain composure.

And talking of steering, the use of an electric assistance system -- as a result of the need to operate without the petrol engine running -- means there is little feedback and a certain amount of vagueness as to exactly where the wheels are pointing.

With the Carsales Network's test loop taking us down through Victoria's Mornington Peninsula, there was, as you would expect in June, a fair amount of moisture on the roads and here, the car's electronics occasionally seemed to get confused.

According to the graphic on the dash, sometimes we got rear electric power and sometimes the car relied on its sophisticated VSC stability control to keep the RX on track. While it did always remain on track, there was a discernible difference in the feel with the car reacting differently on different surfaces. Not entirely confidence inspiring.

Few who spend an extra $10,000 for the environmental benefits of a hybrid are likely to drive the RX hard (and heaven forbid any suggestion of heading offroad!). More than likely it will be used for the school run where its urban economy, refinement and high level of creature comfort benefits make it an appealing option. If you really must drive an SUV, that is!

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