From flexi-top to flexi-power

Two of the traditional downsides of any convertible vehicle are that the foldable roof can take up a lot of room in the boot, and if the roof is of the soft-top variety, it can result in interior noise levels being quite high.

But what if the roof is of the hard-top variety?

If that's the case, then one of those traditional downsides promptly disappears.

That is the case with the new Lexus IS250C, which has a three-part aluminium roof that overlaps and folds all over itself in just 20 seconds to either store itself in the boot, or to flip up again and secure itself over the heads of those sitting in the car.

In typical Lexus fashion, that open-close operation is beautifully done too.

When the roof is folded down, the IS250C offers a classy open-topped motoring experience in which even the airconditioning automatically adjusts itself, so those in the vehicle can maintain their required level of warmth.

When the roof is folded up, a combination of good design and intelligent use of weather strips means the car drives as quietly and securely as any medium-sized luxury vehicle with a permanent roof.

What about the second traditional downside? Ah – no. When this Lexus' roof is up, the luggage capacity is 391 litres, which isn't too bad. But when the roof is down, this luggage capacity reduces to 136 litres, which is about enough to take one overnight bag. However, there are the back seats, which can also be used to store luggage, which is something they would probably be used for most of the time, because a lack of leg room back there means no adult would want to travel too far in an IS250C.

The process one must go through to allow the roof to fold down is quite a complicated one.

First, you have to fix a tonneau-type luggage cover in position in the boot, so the electronic system knows there will be sufficient room for the roof to store itself there. I found the operation of the cover quite fiddly.

Even then, the fold-down may not work, because the vehicle is equipped with sensors to detect the distance between it and an obstacle, stopping or delaying the operation of the roof if there is an obstacle in the rear.

Of course, all this is designed to prevent damage to the Lexus and its roof, so that is good, but it does seem a bit too complicated.

However, once the roof does fold down, this Lexus transforms itself into one of the best convertibles I have yet driven.

Handling and stability are as good as the sedan versions of the IS250, because additional strength has been added to the body for consistent rigidity, whether the roof is up or down.

Not only that, but the convertible is also equipped with Vehicle Dynamics Integrated Management (VDIM), which co-ordinates the car's stability control, anti-lock braking and traction-control systems. So the ride and handling are very good.

Performance is sound as well, thanks to a 2.5-litre V6 DOHC engine with a power output of 153 kilowatts at 6400 revolutions per minute and 252 newton metres of torque at 4800rpm.

Unfortunately, the week that I had the IS250C, it rained the whole time, which meant I had little chance to travel any great distance with the top down. But there were a few times, when the rain started, that I was happy the roof could close in just 20 seconds.

So we spent most of the time with the roof up, which actually wasn't any hardship at all. That's the beauty of hard-top convertibles such as this. When conditions are wet and cold and the roof has to stay up, they are just like any sedan. But when the sun comes out and the weather warms up, they offer that new and desirable top-down dimension to motoring.

ONE of the most advanced vehicles to enter the New Zealand luxury market this year has been the new Lexus RX450h hybrid.

It is an interesting vehicle, powered by a 3.5-litre petrol engine, and equipped with an advanced Lexus Hybrid Drive system, which features a rear electric motor in addition to front electric and petrol motors, combined with a new inverter with improved-cooling performance to raise fuel efficiency.

It drives very well. Not only that, but fuel efficiency in the RX450h is improved considerably over the previous model, and is now 6.4 litres per 100 kilometres, more than 20 per cent better than before and pretty good for a luxury sport utility vehicle with the power of a 4.5-litre engine.

The RX looks identical to the petrol-powered model that has recently been facelifted, but under the skin there are major differences, thanks to the hybrid system.

While both the RX350 and the RX350h have the 3.5-litre V6 engines, in the hybrid, the engine is an Atkinson cycle version.

In this version, the inlet valves are left open for longer, which delays the beginning of the compression stroke and therefore creates a higher expansion ratio.

While the benefits of this are reduced energy losses and better fuel consumption, the big downside with an Atkinson cycle engine is a lack of low-down power. But this issue is instantly removed thanks to the electric power offered via the hybrid system.

Drive this hybrid, and it immediately impresses as a powerful and quiet vehicle. In typical hybrid fashion, the big SUV's inner workings just need to be left alone to do their magic.

It operates mainly and silently on electric power in slow stop-go traffic, and when you need to sneak up the driveway late at night.

On the open road, the petrol motor joins in on the motoring effort when required.

On the inside, this SUV contains all the good things that have been introduced to the petrol-powered RX models, including a revised instrument panel and navigation system.

Central to all this is a centre console with new devices such as a computer mouse-like Lexus Remote Touch, and a multi information switch, which clearly separate the interior into two distinct zones – a "display zone" to provide information, and the "operation zone" for interaction.

But in this vehicle, the conventional tachometer has been replaced with a hybrid system indicator, which encourages the driver to apply the accelerator in a more environmentally friendly manner.

This indicator features a function to display the Eco driving range in addition to the conventional power meter to indicate hybrid-system output force and regenerative charging. In conjunction with the Eco driving indicator zone display, this instils greater environmental and fuel efficiency awareness within each driver, to promote a more environmentally friendly driving style.

A further feature I enjoyed with this car is new Head-Up Display (HUD) technology, which clearly displays information such as vehicle speed and the satellite navigation information on the windscreen in front of the driver.

This new Lexus isn't cheap, at $114,990 for a base model, $124,990 for an SE, and $133,990 for a Limited version. But what you get for the money is very good.

It could be said that the RX might not be the most exciting SUV in the world, but the technology under the hybrid's skin makes it an impressive offering.

- © Fairfax NZ News