In 1927, Prentiss competed in the
Annual Fall Auto Races at
Oakley, Kansas. A win in the ten mile (16 km) race was followed up by second place in the race, despite having a flat tire for the last three laps. taking joint second place in the one mile (1.6 km)
time trial and third place in the race. He finished on the lead lap in 13th place, and won $450 in prize money. In 1934, he entered the Indianapolis 500 again. He practiced with two cars, but was not fast enough in qualification to be able to start the race.{{cite web == Motorsports career results ==