Conversation so far:
Where was Piquet born?
Piquet was born in Rio de Janeiro, then the capital of Brazil.
Was he interested in racing or races as a child?
Piquet started kart racing at the age of 14.
Did he race with friends or was there a race for kids?
Upon returning to Brazil, Piquet and three friends brought a 20 hp cart and participated in Brazilian go-karting (1971 and 1972 national champion.
How long did he race with the 20 hp cart?
CANNOTANSWER.
What did he do after the 1972 and 1972 national championship?
and in the local Formula Super Vee 1976 championship.

Question: What did he drive after the 20 hp cart?
Self-contained rewrite: What did Nelson Piquet drive after the 20 hp cart?