Kulwicki grew up in Greenfield, Wisconsin, a suburb of Milwaukee known for its Polish-American neighborhoods, near the Milwaukee Mile racetrack. After his mother died, his family moved in with his grandmother, who died when Kulwicki was in seventh grade. A year later, his only brother died of a hemophilia-related illness. Kulwicki attended Pius XI High School, a Roman Catholic high school in Milwaukee, and received a bachelor of science degree in mechanical engineering from the University of Wisconsin-Milwaukee in 1977.

Kulwicki began his racing career as a 13-year-old kart racer. His father built engines as the crew chief for Norm Nelson and Roger McCluskey's United States Automobile Club (USAC) racecars. Because his work involved travel, Kulwicki's father was unable to help his son at most kart races, so Kulwicki's resourcefulness was often tested trying to find someone to transport his kart to the track. Even when Kulwicki asked his father for advice, he typically ended up doing most of the work himself. "I showed him how", Gerry Kulwicki said. "And he said: 'Why don't you do it? You can do it better.' And I said, 'Well, if you do it for a while, you can do it better.'"  Many local-level American racetracks host their own season championships. In Wisconsin, numerous locations held dirt and asphalt short track racing. Kulwicki started driving stock cars at the local level at the Hales Corners Speedway and Cedarburg Speedway dirt oval tracks. In 1973, he won the rookie of the year award at Hales Corners Speedway in the Milwaukee suburb of Franklin, and the next year started racing late models - the fastest and most complicated type of stock cars raced at the local level - at the same track. That season, he won his first feature race, at Leo's Speedway in Oshkosh.  Kulwicki moved from dirt tracks to paved tracks in 1977. He also teamed up with racecar builder Greg Krieger to research, model, engineer, and construct an innovative car with far more torsional stiffness than other late models. The increased stiffness allowed the car to handle better in the corners, which increased its speed. Racing at Slinger Super Speedway, he won the track championship in 1977. In 1978, Kulwicki returned to Slinger; that same year he started racing a late model at Wisconsin International Raceway (WIR), finishing third in points in his rookie season at the track. In 1979 and 1980, he won the WIR late model track championships.  In 1979, Kulwicki began competing in regional to national level events sanctioned by the USAC Stock Car series and the American Speed Association (ASA), while remaining an amateur racer through 1980. When Kulwicki raced against future NASCAR champion Rusty Wallace in the ASA series, the two became friends. Kulwicki's highest finish in the ASA season points championship was third place, which he accomplished in both 1982 and 1985, with five career victories and twelve pole positions. Answer this question using a quote from the following article:

When did he start racing?
Kulwicki began his racing career as a 13-year-old kart racer.