Through an interpreter, project general manager Keiichi Yoneda gave a few reasons. The car's A-pillars are strong, active pop-up rollover bars require more space and result in a smaller boot, and a car occupied with four people is unlikely to roll over.

As you can see, they are not very convincing answers.

The real reason came to me when I took delivery of the test-car. With the roof up, those scalp-protecting hoops almost touch the top end of the rear windscreen. There is just no more space for bigger rollover bars.

Lexus may have mastered quality but evidently not design.

The IS-C is Lexus' first full four- seater convertible. It is also the first car with a foldable hard top that is designed and built in-house (the others commission specialist roof-makers to do the job). Alas, this first attempt has resulted in the aforesaid bar-roof conflict, not to mention impaired rear visibility. The folded roof also takes up a lot of boot space, leaving enough stowage for a golf bag and little else.

There are other things about the IS-C that make you go "hmmm". Its slab- sided styling is a tad yesterday, with a conservative front end that works well for the IS sedan it is based on but is downright boring for a topless car. The overall profile is pleasant but in this day and age, that is not quite enough. And the funky new colours, including purple and shocking metallic blue, do not suit the conservative shape.

Like I said, design does not seem to be Lexus' strong suit.

The car is well built otherwise and the Lexus hallmark of quality is evident everywhere. The roof's folding mechanism is both smooth and clever. If it senses the car is parked too close to a wall or if someone is standing too near the boot, the roof will not retract.

Source : http://motoring.asiaone.com/Motoring/Test%2BDrive/Story/A1Story20090713-154305.html