Davis was "sort of" sponsored by Saab as far back as the 1960s. After meeting with Ralph Millet, president of Saab Motors USA at the Detroit Auto show in the mid-60s, Davis left with Millet's personal Saab 96 850GT to use for rallying. He drove several different Saabs in rally comptetion in the 1960s, 1970s and 1980s.
Davis won the fledgling SCCA ProRally Production Class in a Saab 99 in 1980-81. He was so successful with the Saab that Ford hired him to drive a Ford Escort in 1982, an effort that was not very successful.
Here is Jon with his long-time co-driver Harry Ward at the 1981 Sunriser rally in Ohio. Photo by Rick Corwine.
Though BFG was the major tire sponsor at the time, those look a lot like Nokia Hakkapellittas on the 99.