WHEN you've built a radical looking new car that's become a best seller all around the globe how do you boost sales even more?

Well in the case of the Lexus RX 450h the answer seems to be simple - add more seats.

The Japanese luxury car maker has stretched the big SUV by 110mm - just over four inches. And that's enough to allow it to fit in seven rather than five seats, appealing to a whole new category of buyer.

Even in five-seater format the RX 450h is a large, futuristically styled car but with the extra inches it takes on an even more dramatic presence which makes many of it competitors look not only small but old fashioned.

Cleverly, despite the increase in size, the seven-seater has retained it's sleek, coupe-like profile.

And Lexus being Lexus the two third row leather seats are not only full size but the car gets the bonus of triple zone air conditioning with separate controls for those at the back.

When you need additional luggage space the third row seats automatically fold completely flat into the floor electrically at the touch of a button, and return to the upright position the same way

To give those travelling in the new seats more legroom the second row of seats has been set higher allowing them to get their feet underneath.

Even so while they're fine for small children they're tight for adults, and probably more suited to a trip to the local pub than a long journey.

The bonus of the car's extra inches, however, is that when the third row seats are not in use passengers in the second row get an abundance of leg room allowing them to stretch out fully.

The interior of the RX 450h L is typically up-market Lexus with a nice blend of black leather, dark wood inlays and contrasting brushed aluminium detailing.

In the centre of the dashboard there's a huge central colour display screen - operated by a computer style mouse near the gear shift - for onboard features like radio and satellite navigation while a fighter pilot-style head-up display means you are always aware of your speed.

On the road the car glides along serenely and in silence thanks to the 3.5-litre petrol V6 engine and two 650 volt electric motors, one for each axle, giving the bonus of four-wheel-drive and lively performance.

And it's surprising just how often this large hybrid allows you to run on electric power only, ensuring trips to the petrol station are few and far between.

If you want to liven things up a little, however, you can always change the driving mode to Sport or Sport+ and feel the surge in power as well as the dramatic firming up of the suspension system.

As you make the change the economy metre in front of you converts to a conventional rev counter.

The RX 450h L Premier is one of those few cars which seem to take the stress out of long distance driving.