In 1899, Albert Champion came to the U.S. as a champion bicycle racer. He found a job with the Stranahan brothers, who had started Champion Spark Plug Company in 1905 or 1906 and began production in 1907.
Champion was not happy in his job because he had no control over his work. He already had at least one spark plug patent (from 1898) before leaving Europe.
In 1908, he went to see William C. Durant of the Buick Motor Co. Durant asked to see some of his prototypes. Buick at that time was using Rajah spark plugs. Durant thought they could manufacture spark plugs to Champion's design cheaper than buying them from Rajah, and set Champion up in a workshop in Flint, Michigan as part of the budding auto industry there.
Champion went to work producing spark plugs to be used in Buick automobiles. Champion and Durant formed "Champion Ignition Co." Very shortly later, the Stranahan brothers ("Champion Spark Plug Co.") informed them they could not use the name "Champion" as they had it trademarked. At that time the name was changed to reflect Champion's initials. "AC Spark Plug" was trademarked in 1908. In 1927 AC became a division of General Motors.