IN THIS FEATURE Early days Popular personal luxury The Squarebird Projectile styling Growing again Ugly duckling Aerodynamic phase Temporary retirement New Thunderbird

For 1967, the Thunderbird reverted to the traditional body-on-frame construction method. Longer again, a four-door model with an extra pair of 'suicide' rear-hinged doors was offered, and nearly 25,000 of these were sold alongside the two-door coupes. All Thunderbirds gained a longer bonnet and shorter rear deck, which was accentuated further in the 1970 redesign which also brought a front grille and bonnet that integrated fully into the bumper, the 'poke-thru nose' extruded aluminium grille and twin headlights.

'Poke-thru nose' featured in 1970 redesign

Ever more opulent and ever less sporty, the Thunderbird was treading a fine line between luxury and vulgarity: the Neiman Marcus department catalogue offered, in 1971, "his and her Thunderbirds" - twin cars equipped with telephones, tape recorders and other special equipment, costing $25,000 the pair. The Thunderbird was now competing against cars like the bloated Oldsmobile Toronado, rather than the Corvette. The millionth Thunderbird was sold in 1972, but Ford had to react to the threat of energy shortages and the oil crisis a year later. Work began on a new, smaller model, which made its debut in 1977; very similar to its sister model, the Mercury Cougar, it was based on a saloon platform, was ungainly and overdone to look at and undistinguished to drive - yet around 318,000 were sold up until 1980.