Lexus RX 400h 2006 Review

What we liked
>> Low fuel consumption
>> Strong performance
>> Plush comfortable ride

Not so much
>> Slightly sluggish CVT
>> Light and lifeless steering
>> Average dynamics

That is not to say it is not offering an alternative to traditional petrol power or that it isn't developing vehicles that take into account bottom line fuel costs and the environment, it's just that its focus is petrol electric hybrids.

Already the company offers the mid-sized sedan GS450h, this month it launched the first hybrid all-wheel drive SUV in the form of the RX400h and next March it will introduce the world's first V8 petrol electric hybrid drivetrain in the new big LS600hL sedan.  

According to the company, it is determined to make hybrid drivetrains its big point of difference against its German rivals that are all increasingly offering diesel passenger cars and soft-roader SUVs.

While Lexus' hybrid range certainly does stand out from the crowd in terms of powertrains, it is not simply point of difference that is driving the Lexus product lineup. Lexus built its brand in the US and as far as looking at alternative drivetrain technologies for the future, the US market favours petrol electric hybrids while Europe is predominantly a diesel market.

Lexus does sell diesels in Europe and if the Australian market gives the thumbs down to hybrids in favour of diesel, it won't be too long before the luxury arm of Toyota adds an oil burner to the local market but in the meantime, Lexus' environmental conscience -- and those of its owners -- is to be appeased by hybrids.

The latest to land is the RX400h -- based on the existing RX350 five-seat soft roader SUV and as you would expect, the hybrid version sits at the top of the range priced at $94,100 carrying a $10,000 premium over the petrol only RX350 Sports Luxury model and $19,300 hike over the entry level RX350 Sports.

FEATURES
At a casual glance, the average punter won't notice the difference between the RX350 Sport Luxury and the hybrid version as apart from the badge, there is no difference in the exterior style, size or features.

Like the rest of the range, the 400h is a reasonably stylish sort of SUV that eschews the big macho body bulges in lieu of a more urban-friendly sleeker and car-like design. Inside you are not likely to immediately notice that this car uses a hybrid drive system until you turn the key. For in addition to the usual array of satnav and audio functions accessible via the centrally mounted touch screen, it also displays a complex graphic that features electric motor, battery and petrol engine diagrams that tells you exactly where the power and torque are coming and going at all times courtesy of an array of different coloured arrows. It is more high tech gimmickry rather than offering any real function -- other than to let you know that you are indeed driving a hybrid -- as the only thing you need to know at the end of the day is that you are actually using less fuel than an equivalent petrol engine.

The bulk of the standard equipment is shared with the Sports Luxury RX350 and includes climate control air conditioning, 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.

Apart from the screen, the 400h also gains electric power steering incorporated into the Vehicle Dynamics Integrated Management system (VDiM) -- the latter is an electronic stability control system that adds steering assistance when necessary -- heated front seats and a range of minor cosmetic treatments.

COMFORT
As a vehicle designed primarily for the US market, comfort is a big factor in the Lexus soft-roader and as you slide in behind the wheel, the big plush leather trimmed seats provide the first point of contact as evidence.

The seats are big, with plenty of cushioning but unlike some others designed for American bodies, they also offer a reasonable degree of support. There is plenty of space up front and the all-electric adjustment for the driver's seat and steering column means that getting a good driving position is easy.

In the rear, there is good head and legroom for a couple of adults and over short trips you could squeeze three across the 40/20/40 split rear seat.

Like the petrol RX models, the 400h uses a strut front and rear suspension that is tuned for comfort rather than handling and it certainly lives up to that bias delivering a compliant and reasonably controlled ride.

With its electric drivetrain, there is no shortage of assistance systems either including anti-lock brakes with brake assist and electronic brakeforce distribution, stability and traction control and adaptive headlights.

The airbag count numbers seven -- dual front, front and rear side, side curtain and driver's kneebag -- and all five seats have three point seatbelts and adjustable head restraints.

MECHANICAL
This is the bit where the 400h gets tricky and what obviously differentiates it from its petrol engined kin.

Under the bonnet powering the front axle is a combination of a transversely mounted 3.3-litre V6 petrol engine that produces maximum outputs of 155kW at 5600rpm and 288Nm at 4400rpm and an electric motor/generator that develops 123kW of power at 4500rpm and 333Nm of torque from 0-1500rpm.

A second smaller 50kW/130Nm electric motor drives the rear axle thereby alleviating the need for any rear drive shaft for the all-wheel-drive system. Maximum power, however, is not a simple case of adding up the numbers and according to Lexus, the maximum combined output is 200kW. This compares to the 203kW on offer in the 3.5-litre petrol RX350 with the comparative official ADR81/01 combined fuel consumption listed as 11.2l/100km for the 350 vs 8.1l/100km for the 400h.

During start up and at low speeds, the car is powered by the electric motors with the petrol engine kicking into life when more power is needed for acceleration and cruising at higher speeds.

The rear electric motor basically provides the traction assistance in terms of the AWD system  -- dubbed E-Four -- and only operates when necessary. The maximum torque split ratio front to rear is 72/28.

Energy generated under braking and for running the electric motors is stored in a large capacity 288-volt battery located under the rear seat. In addition to running on a combination of petrol and electric power to save fuel, the petrol engine also cuts out altogether when the car is stopped at traffic lights.

As well as the actual powertrain, the 400h also features a unique transmission that drives the front wheels and uses a compound set of planetary gears that act as a continuously variable automatic transmission (CVT). How this translates for the driver is that it is a simple case of shifting the lever into D for drive and pushing the accelerator. Unlike the current trend in CVTs, there is no "virtual manual" gear option.

COMPETITORS
In terms of direct competitors, there is nothing else in the market that offers a hybrid drivetrain in an SUV. However, with the growing concerns over fuel prices, many in the luxury SUV market are opting for diesel power that also offers significant fuel consumption and emission benefits over petrol powered SUVs. According to Lexus, the 400h benefits from a 14 to 20 percent fuel consumption advantage compared to the other automatic transmission diesel models in the luxury SUV segment.

Of these, the prime rivals for the five-seater Lexus are the $84,300 BMW X5 3.0d which lists an official fuel consumption of 9.4l/100km and the $90,900 Mercedes-Benz ML 320CDI which according to the official ADR fuel figures uses an average 9.6l/100km.

Other luxury five-seater diesel SUVs in the same sort of price bracket include the 2.5-litre Audi Allroad TDI, Range Rover Sport TDV6 and Volkswagen Touareg.

That said, there is enough power from the electric motors to move the 2-tonne SUV off the line with a decent amount of speed and a firm thrust of the right foot has the petrol engine quickly and effortlessly kicking into life adding to the forward motion.

Even with the petrol engine running, the ambience in the cabin is quiet and refined and from the driver's seat, apart from the visual display of the various power modes, there is no discernible difference to driving a petrol-only car as the system goes about its way without any noticeable differences in the drive experience.

The CVT is smooth but does seem ever so slightly slow to respond to throttle input whether you are pushing hard off the line or when overtaking.

Like the rest of the RX range, the 400h is not the most dynamic of SUVs with the suspension tuned more for ride comfort than handling and on initial and brief impressions, there is a little body roll through corners although it does seem to feel quite solid on the road.

The drive route for the launch was carefully chosen to cover largely urban roads where the speed limit rarely exceeded 80kmh so there was little chance to really wind up the car and test its dynamics or what the fuel consumption might have been with constant running of the petrol engine. Over the course of the 130km route out through the suburbs of Sydney, Carpoint returned an average fuel consumption of 8.9-litres/100km -- not far shy of the quoted ADR figure of 8.1l/100km -- indicating that at least in urban conditions, the RX400h does live up to its claims of low fuel usage and consequently lower emissions than in a typical petrol SUV.

With a $10,000 premium over the equivalent petrol engined RX, if you were to work out the payback time in terms of fuel consumption alone, you would be talking years but that doesn't take into consideration retained value differences or the immeasurable "environmental conscience" factor that comes with driving a hybrid vehicle. And with little discernible difference in the actual driving characteristics of the car versus its petrol equivalent, the latter can make the hybrid RX a very appealing product.