Lexus beating the green odds with its RX 4x4

4x4s have a big image problem and it gets worse the bigger they get. The Lexus RX450h might be the car to change all that with its latest generation hybrid drive system bringing much improved fuel and CO2 returns, enabling running costs more in keeping with those of a mainstream family hatchback.

Wednesday, 23rd March 2011, 9:32 am

A detailed safety specification and Lexus build quality could make this an attractive car for those with the cash and strong green principles.

In case you’re still unfamiliar with hybrid technology, it’s essentially a method of powering a car using a combination of an internal combustion engine and electric motors.

Diesel hybrids have been mooted but the RX450h and the other Lexus hybrid models all have petrol engines supplemented by battery driven motors. The petrol unit in question here is a 246bhp 3.5-litre V6 with a number of innovative features designed to enhance its efficiency.

It’s supplemented by a pair of electric motors, one for each axle, which give the four-wheel-drive Lexus a maximum potential output of 295bhp.

Though in theory, that’s a ten per cent increase in power over the old RX400h, the 0-60mph sprint time (of 7.8s) and the 124mph top speed are pretty much unchanged.

Still, while this doesn’t place the car in the league of the quickest V8 luxury 4x4s, it remains pretty rapid for a car of the RX450h’s size and weight.

The RX450h needs a luxurious ride and a responsive chassis if it’s to compete with the leading luxury 4x4 contenders, some of whom are remarkably agile on the road given their bulk.

To this end, Lexus has engineered a clever and much improved suspension set-up comprised of MacPherson struts at the front and a double wishbone arrangement at the rear while giving the car a wide track for extra stability and a highly rigid body shell.

Only the top specification models get electronically controlled air-suspension but all RX450h models feature VDIM Vehicle Dynamics Integrated Management that controls and distributes power from the complex drive system.

There are obvious echoes of the old RX400h in the styling of the latest RX450h.

The look has been kept fairly conservative and evolutionary in the best Lexus traditions but there are engaging details such as the heavy shoulder line and the way the headlights integrate with a front grille that features a blue-tinted Lexus badge at its centre.

A turning radius of 5.7m hints at decent manoeuvrability and inside there’s a 495-litre boot adding to the practicality of the car.

The seats split 40:20:40 and can slide backwards and forwards to increase the luggage space behind.

There are also levers in the boot which fold the rear seats down at a single touch for greater convenience when loading.

Lexus continues to champion hybrid technology and with the latest RX450h, its argument looks more compelling than ever.

The mix of a petrol engine, batteries and electric motors yields fuel economy and emissions which far exceed the expectations we have of full-sized luxury 4x4s.

Perhaps the RX450h isn’t the most immediately desirable contender in the luxury 4x4 segment but the more buyers learn about the technology and its capabilities, the more their interest is likely to grow.

If we are going to drive full-size 4x4 vehicles in the future this Lexus could be giving us our clearest indication yet of what they’ll be like.