Question: The 1967 Trans-American Championship was the second running of the Sports Car Club of America's Trans-Am Series, which year would also mark the debut of Mercury, with Dan Gurney winning at Green Valley for the company in its new Cougar, Gurney also reached racing's highest levels starting in which year?
Sentence (from "1958 United States Grand Prix for Sports Cars"): It was the fourth and final round of the 1958 USAC Road Racing Championship season, the seventeenth round of the Sports Car Club of America's Pacific Coast Championship, the second running of the Riverside Grand Prix, and the first post-World War II running of the United States Grand Prix.
Relevant evidence: No