Motoring: Quiet time

One of the quirks of hybrid vehicles is that after a while, you actually start trying to be an eco warrior.

The urge to keep the dashboard needle in the green zone of fuel efficiency overcomes you like a slowly spreading stain.

The thought of stomping on the accelerator and racing into the power zone suddenly fills you with dread and saving the planet one trip at a time becomes your ... only ... reason ... for ... living.

Ok, I exaggerate, but your driving habits do change.

That’s made a lot easier by the dashboard dial that shows when the batteries are being charged, when you are driving at your most economical and when you’re spending the kids’ inheritance.

It’s also helped by the fact that with the Lexus RX450h, you’re not about to smoke anyone at the lights. It’s a conservative and comfy SUV and it drives like it.

You quickly realise that you don’t actually get much of a rush from the pick-up and all a heavy right foot does is pick the notes out of your wallet.

So you start seriously trying to improve your fuel economy. Around town I got 9.1l/100km, which beats a few four-cylinder cars and is pretty impressive given the Lexus with its extra batteries and electric motors tops two tonnes.

Officially the combined figure is 6.4l/100km but that must have been measured on a long downhill straight with a following breeze on a sheet of glass.

Even better was the test I did with a full car and luggage towing a trailer over more than 500kms. For that, it added only another litre per kilometre to 10.1l/100km. That’s impressive.

It was the first test of this vehicle with a trailer in Australia and it performed beautifully.

There was never any hesitation, even uphill, as the 3.5 litre V6 and electric motors worked together to meet the power needs.

The V6 produces a maximum 183kW of power at 6000rpm and 317Nm of torque at 4800rpm, while the front electric motor delivers 123kW with 335Nm of instantaneous torque. The RX450h also has a 50kW electric motor to power the rear wheels and it can run on electric power alone at low speed for up to two kilometres – great for sneaking home late at night.

Any energy not used immediately is stored as electricity in a nickel metal hydride battery under the back seats, which is how Lexus can fit the RX450h with a tow bar.

Other hybrid cars keep their batteries in the rear, which prevents them from towing.

While Americans get the choice of a dozen or so hybrid SUVs, only the $177,169-on road Porsche Cayenne S Hybrid is an alternative here.

Lexus, and by extension Toyota, has had plenty of experience with hybrids. The first of the SUV versions was the RX400h, which was released in 2004 based on the RX330 and it arrived in Australia in 2006.

In 2009, Lexus extended the hybrid battery warranty to eight years or 160,000km, so you can forget worrying about the replacement cost.

The RX450h’s shortcomings are few. While it is a five-seater, the fifth seat in the centre back is an option only for short trips as it’s hard and uncomfortable and the front centre console has a feature I hope will be killed off quickly – a mouse-like control for the screen functions.

Manoeuvring the joystick to get the pointer in place on the screen distracts the driver far too much and takes too much concentration. Bad idea, Lexus.

On the positive side, the driver’s seat does the nifty trick of sliding backwards as the steering wheel rises to allow easier access when the ignition is switched off.

It also has active cruise control, which monitors the road to maintain a set distance from the vehicle ahead. If that distance closes or another vehicle appears in front, the cruise control reduces your speed and even applies the brakes if necessary.

The test car had separate screens in the rear for individual or combined viewing.

The new model RX450h has the new more aggressively style grille but will have a largely unchanged interior.

The basic RX450h Prestige has a drive away price of about $98,000.

• Tweet