His reputation as a solid "team player" and excellent test and development driver earned him an invitation to join the works Honda F1 team for 1965, for whom he scored his one and only GP win, at the 1965 Mexican Grand Prix. The win was also Honda's first in Formula 1. Ginther averaged over the curving track in the 65 lap Mexico City event. His speed eclipsed the previous course record of established by Dan Gurney in 1964. It was the first time Honda had entered the Mexican Grand Prix. Honda reentered international competition in the 1966 Italian Grand Prix. The team was three years old and had encountered difficulty in the preparation of a larger engine. Ginther led in Italy before his car crashed into a retaining wall and he broke his collarbone. He signed with the Eagle F1 team in 1967 and raced in the Race of Champions. His last race entered was the Monaco Grand Prix, but he failed to qualify.