The main advantage to using carbon fiber is its immense strength to weight ratio.  It actually has about half the strength of steel but only one-fifth of the weight.  Stiffness is about five times that of steel per unit weight.  Thus a car can be lighter and yet have endure enormous crushing and torsional loads.  This makes it safer in car crashes, enabling many drivers to walk away from 200 km/h collisions.  The stiff chassis also allows designers to optimize suspension settings as they know that the chassis will not flex or bend much when the suspension hits bumps or curbs. 

You might be interested to know that aside from the chassis, many of the components in an F1 car are made from carbon fiber.  The suspension arms holding the wheels are also carbon fiber, are as the airbox channeling air to the engine.  (The airbox opening is right above the driver's head.)  Seats and steering wheels are also carbon fiber.  Brakes are also made from carbon material, enabling them to endure intense heat during the race; they can slow the car from 300 km/h to about 40 km/h in just a few meters. Finally, some road cars have actually been constructed from carbon fiber.  The McLaren F1 and Ferrari F50 are two very-high-performance road cars that benefit from the high strength and low weight of this material.  However, note their price tags of about $500,000 for the F50 and $1,000,000 for the F1.  A sheet of carbon fiber costs up to $550 per square meter.  This is the main reason why we won't be seeing carbon-fiber Corollas or Civics on the street soon. 



The nose of the Jordan Mugen-Honda. With a top speed of around 350 km/h, a curb weight of less than 1000 kilograms, the Formula One car is the epitome of high speed design and engineering.