Gordon Wilkins covers the world of motoring with Michael Frostick.

Porsche were sports car champions of the world in 1969, winning the Targa Florio and the 1,000 kilometre events at Spa and Monza. They also came first in the Monte Carlo Rally and the Acropolis Rally, and the new Porsche 917 achieved a speed of nearly 240 miles an hour at Le Mans. What explains the success of this small Stuttgart firm in rallying and racing?
Extensive use of light alloys and a high performance engine over the rear driving wheels give the Porsche excellent speed and road-holding - Dr Ferdinand Porsche also designed the first Volkswagen - but the car is expensive and not without its critics.