1975 Bluebird U 1600GL: The 610 (fourth-generation) was launched in August 1971, badged as the "Bluebird U". It was on sale for a while alongside the 510. Its distinguishing feature was its styling, with generous curves and well-rounded lines. Both the sedan and the hardtop were available in 1800 and 1600 versions. The 1600GL was equipped with front disc brakes, a wooden steering wheel, and a heated rear window as standard.