The personal-luxury Grand Prix was a top-seller in the 1970s, including this 1974 Pontiac Grand Prix shown here.

1970s Pontiac Grand Am and Pontiac Grand Prix

The story of the larger 1970s Pontiacs is about as exciting as rust -- which many of them did all too quickly. Basic designs were inevitably shared with sister GM intermediates and standards, but workmanship often seemed half a notch lower.

By late decade, though, both the LeMans/Grand LeMans and Catalina/Bonneville had evolved into more sensible, solid, and saleable cars much better suited to the times than the aging hulks that Chrysler and Ford still peddled.

Midsize Pontiacs quickly turned from their assured roadability of the 1960s to an emphasis on luxury and convenience. One bright exception was the Grand Am. Introduced as part of the redesigned 1973 line with "Colonnade" styling, this LeMans-based coupe and sedan were billed as combining Grand Prix luxury with Trans Am performance, hence the name.

The idea was largely owed to assistant chief engineer Bill Collins, who'd been heavily involved with the original GTO, and chassis wizard John Seaton. Their aim was to approximate European sedans like the Mercedes 250/280 and the BMW Bavaria at a third to half the money.

While some features strained at mimicry -- a Mercedes-like jumbo-hub steering wheel, for instance -- the "G/A" was, on balance, one of the most impressive big Detroiters in a generally dull Detroit decade. But it failed to make a strong impression in a market where most buyers looked for either everyday transport or as much glitz as their money would buy.

Grand Am attracted only some 43,000 sales in its debut year -- mainly coupes -- then plunged to 17,000 for '74 and only 11,000 or so for '75. To no one's surprise, it subsequently disappeared. Curiously, the name resurfaced on a coupe and sedan in the downsized 1978 LeMans line, but these cars were nowhere near as grand and were similarly short-lived, the sedan canceled after '79, the coupe a year later. But the Grand Am name would be back later.

Rivaling Firebird for '70s success was the personal-luxury Grand Prix -- in some of these years Pontiac's single best-selling model. It had been reborn for 1969 as a lighter, quicker midsize coupe on a 118-inch-wheelbase "A-Special" platform that Chev­rolet would crib for its similarly posh (and popular) Monte Carlo.

Offered with both 400 and 428 (later 455) V-8s, the new GP was a handsome brute, with a short-deck notchback profile and a distinctly Pontiac face ahead of a mile-long hood. Inside was an innovative curved instrument cluster bringing all controls within easy driver reach.

Cribbing Model J and SJ nomenclature from the revered Duesenberg was a vain attempt at cachet, but the public applauded this Grand Prix, snapping up nearly 112,500 of the '69s. Sales were healthy through the end of this design generation in 1972, when just under 92,000 were retailed. Styling didn't change much, and although horsepower went down a bit after 1970, big-block performance remained quite good.

Pontiac continued this successful formula through GM's 1973-77 Colonnade intermediates, when the GP went to the same 116-inch wheelbase as Monte Carlo. A vertical grille and a roof with a '67 Cadillac Eldorado-like crease through the backlight set these GPs apart. Interestingly, Grand Prix notched a new all-time sales record for 1977, close to 288,500. The '78, unfortunately, was much more like LeMans, downsized to the same new 108.1-inch platform and looking less distinctive.

Yet sales weren't vastly affected: some 228,000 for the model year. Clearly, the GP had succeeded in a way that various gussied-up Luxury LeMans and Grand LeMans variations couldn't. Without it, Pontiac wouldn't have weathered the ups and downs of the '70s nearly as well.

For more on the amazing Pontiac, old and new, see:

For more on the amazing Pontiac, old and new, see: