BIG NAME IN RACING can be summarized by three crossword solutions: UNSER (5 letters), ANDRETTI (8 letters), and NASCAR (6 letters). Unser is a surname of a family of American racing drivers, the most famous of which is Al Unser Sr., who won the Indianapolis 500 four times. Mario Andretti is an Italian-American former racing driver who won the Formula One World Championship in 1978 and the Indianapolis 500 in 1969. NASCAR is an American auto racing sanctioning and operating company that is best known for stock car racing.