Marshall was a motorsports enthusiast and competed in the last running of the Cannonball Baker Sea-To-Shining-Sea Memorial Trophy Dash, better known as the Cannonball Run, in April 1979. Teamed with Sports Car Club of America racers Dave Faust and Kirby Goodman, Marshall drove a Chevrolet Malibu with the 9C1 Police Patrol Package and a 350 cubic inch LT-1 Z-28 Chevrolet Camaro engine, finishing 13th in a field of 47 competitors, completing the run from Darien, Connecticut, to Redondo Beach, California, in 36 hours, 51 minutes. Marshall wrote, "Over two decades later, the laughs and the memories are still fresh. I was fortunate to be involved".
