Targa and drag coefficient

[Ian Chapman]

Can't quote Cd figures - but any convertible will be faster with roof up
- by virtue of a cleaner air flow along and exiting the car. The shape
of the back of a car is one of the most important things in clean air
flow - obviously frontal area makes a difference. Smooth surfaces and
smooth transitions make a fast car. In ideal conditions a hard top MX5
maybe slightly faster again than a soft top up.

Lotus Sevens even with very grunty engines can do 0-100 in a few
seconds but top out at a bit over 100mph - not a great shape and lots of
exposed bits but have a reasonably small frontal area.

If you want the perfect aerodynamic shape - look to nature - the
classic rain drop. It is free to form whatever shape it wants as it
flows through the air. Look at tapered engine cover of an F1 car.

Many Mini Seven racers liked Riley Elf bodies (remember that cute bum)
because it gave them a few extra mph at the top end. Hmm - so J-Lo
should be a very fast runner!

Ian