Piet got his first foothold in motor racing as a mechanic, indeed he workied his pasage from Durban to London in order to learn about racing cars and spent a short spell working for Colin Chapman.
On his return to his homeland he found employment with Syd van der Vyver who also gave him the chance to his first chance to race. Moving to Johannesburg, he helped Doug Serrurier and Ernest Pieterse in building the Alfa special in 1960, but it was 1962 before the eager de Klerk was to get behind the wheel.
de Klerk quickly began to gain good placings with the car and was subsequently entrusted with a Brabham-Climax with which he was able to challenge more strongly the local maestro John Love.
Piet, however, always seemed to be bridesmaid, finishing second on numerous occasions before temporarily abandoning single-seaters at the end of 1965 when Mike de Udy offered him the chance to race abroad in his Porsche Carrera 6 sports cars. He finished 6th at Le Mans in one of them in 1966 driving with Udo Schütz.
In 1967 he drove a Lola-Aston Martin at Le Mans, before resuming his South African career in late 1968 with Love's old Brabham BT20 before once more concentrating on sports cars into the early seventies.
In 1969 he drove a Lola T-160 at Le Mans with Chris Irwin but went out after 20 minutes.
He retired from driving in the late 1980s but still visits races. Now lives in the Transvaal and owns a Steyr motor dealership in Cape Town.