Take your top off

Published in City Tribune 3rd March 2007

By Tushal Bhadang

Call it fashion, call it passion, no experience compares to the pleasure of driving with the wind in your hair, absorbing the landscape and being one with the car as you dominate the curvaceous Riffa roads. A convertible car captures this feeling of oneness with the practicality of a conventional roof (hard-top) and the pleasure of lowering the same when the sun is shining. Designing a convertible car is not as simple as chopping off the roof and installing a folding cloth (soft-top). Issues pertaining to structural strength and aerodynamics have to be considered in the design stage. Addressing these issues is what raises the price of a convertible car as compared to its fixed roof model. Technically the roof of a car keeps it from twisting and bending.

A car without a roof is like a suspension bridge without cables. This requires the bottom part of the car to be extra stiff with heavy reinforcement brackets which increase the weight of the car. Usually, with their top down cars are less aerodynamic than with fixed roofs. A long, flowing roof smoothes the airflow over the car, resulting in less drag. Have you ever seen people driving a convertible with their hair blowing forward? This happens because the fastmoving air coming off the top of the windshield encounters the slow-moving air inside the cabin. This can be uncomfortable for the occupants, and can increase the aerodynamic drag. A glass shield behind the headrests blocks this air, making the cabin quieter and more comfortable, as well as improving the aerodynamics.

A soft top requires the driver to latch and unlatch the roof manually after electronically raising or lowering it, in a Honda S2000 for example. Coming to hardtops, the Lexus SC430 is almost as aerodynamic with the top down as it is with the top up because of its hard metal fold down roof. This car is a hardtop convertible. As a hardtop, the car makes no compromises: The ride is quiet and the structure is stiff. With a push of a button it becomes a convertible. You don’t even have to undo any latches.

The roof on the SC430 folds in half and stows in the boot. When you press the button to lower the roof, the windows roll down and the boot opens. It opens the opposite way, after which the roof starts to open, folding in half as it heads for the boot. The roof folds over until it is fully inside the boot, at which point the boot closes. The cool thing about the boot is that it can still open just like a regular car boot — although with the roof down, there isn’t much room in there.

Having one convertible is (almost) as good as having two cars in your garage. With the top up, a convertible can be as practical as a coupe. But with the touch of a button (and perhaps a few un-latchings), your ride to work can be a whole lot more fun. Heck one can even have the most expensive cars in the world on convertible form, take for example luxo barges like Rolls Royce Phantom and Bentley Continental GT and super cars like Lamborghini Gallardo, Zonda and Aston Martin even! Though the Mazda MX-5 Miata, Renault Megane CC, Mini Cabriolet and Peugeot 206 CC and their likes should be the should be the one that the masses will be able to afford.