William Carlson Jr. was born in San Diego, California, the son of a Swedish immigrant, who had without benefit of any party affiliation, became the mayor of San Diego in 1893 and was re-elected in 1895.
Billy raced in AAA competitions and in January 1913 he finished third in a two lap race on the streets of San Diego driving a Stutz, before taking a win in a 34 lap race there in March, driving a Benz.
He began 1914 driving a Duesenberg engined Mason to third on the road course at Santa Monica. Then in February he came third in the Vanderbilt Cup driving a Duesenberg.
He then became a works driver for Maxwell. Maxwell had emerged from the ashes of the USMC and the team was run by Ray Haroon. The engines ran on kerosene and Carlson became know as 'Coal Oil Billy' because of this. The other works drivers were Eddie Rickenbacker and Barney Oldfield. He made his first trip to Indy that year, qualifying 5th and finishing 9th and had a number of other top ten finishes.
He entered the Cactus Derby which was run over three days with two overnight stops, one in Needles, California and one in Prescott. The weather was appalling when the twenty drivers left Los Angeles on November 10 en route for Phoenix. After an overnight stop in Needles, the next day Carlson broke a wheel and had to walk to the nearest town for a replacement. On his return he found that his car had been thoroughly stripped.
After problems in the 1915 American Grand Prize and the Vanderbilt Cup with the carburetion, exacerbated by the kerosene, all three drivers threatened to quit unless the team switched to using gasoline. They agreed and Oldfield then won two races with Carlson finishing second. In one of those races in Arizona, Oldfield drove the 25 laps without changing gear or stopping.
He came 9th at Indy in May but was then killed as a result of injuries sustained in the 250 mile Montana Marathon race, part of the AAA National Championship, at the Tacoma Speedway. A tire blew out on his Maxwell and the car flew off the track. His riding mechanic, Paul Franzen, was thrown clear but broke his back on a tree stump and died at the scene. Carson was taken to hospital suffering from internal injuries and a crushed skull, where he died the next day without regaining consciousness. The Maxwell factory team never raced again.