The 1962 X-400 Grand Prix...
The 1962 X-400 Grand Prix as photographed in the design center's viewing courtyard at the GM Tech Center.
From the 1950s through the late 1960s, top executives at Chrysler, Ford, and GM commissioned their respective design studios to create custom rides for their personal transportation. One of those executives was Bill Mitchell, who had come to power in 1958 as Vice President of General Motors Design Staff. Mitchell had replaced the legendary Harley Earl and was instrumental in the fresh new look of GM products throughout the 1960s.
Mitchell had liked the redesign of GM's fullsize models in 1961 and ordered the design staff to produce a 1962 Grand Prix convertible, dubbed the X-400, for him to drive when he wasn't tooling around in his Sting Ray. This wasn't the first Pontiac X-400; both a 1959 and 1960 version had been built based on the Bonneville. Since there was no convertible Grand Prix in the Pontiac product line, a blazing red Catalina ragtop was built specially for Mitchell, and then sent to design staff studios in the GM Tech Center to be converted into a Grand Prix and to add the finishing touches.
The Grand Prix was brand new...
The Grand Prix was brand new for 1962, and its stunning front end was accentuated in the X-400's clean styling. Functional grilles were located in the hood and the word "supercharged" announced that this wasn't just any dolled-up Grand Prix.
The X-400 sported a sparkling red interior and white convertible top, but it wasn't just a pretty face. It packed a solid punch under the hood. Mitchell loved speed and racing, and his Grand Prix was required to kick asphalt.
On the outside, the X-400 was mildly customized. The handsome Grand Prix front end and split grille theme was retained; however, the standard headlamps were replaced by rectangular, single-bulb Cibie Marchal headlamps. Swing-up, mesh grille stone guards covered the Cibies and a unique chrome ornament was mounted on the front centerline of the hood. Also on the hood were two functional grilles, one on each side, with the word "supercharged" boldly announced in chrome block letters.
On the flanks were brushed aluminum concave moldings, and dual exhausts exited through twin ports at the rear of the quarter-panels, just ahead of the back bumper. Pontiac's unique eight-lug aluminum wheels were mounted on whitewall tires. The fabric top stack was covered by a fiberglass top boot, and body-colored Talbot-style outside rearview mirrors graced each door.
A unique, three-blade ornament...
A unique, three-blade ornament was located at the front of the hood centerline. The addition of this ornament is puzzling for 1962, since it's more like a throwback to the excess chrome of GM cars of the late 1950s.
The interior was also mildly customized with red carpeting, red leather thin-shell racing-style bucket seats, a padded console between the seats, and special brushed-aluminum door panels with red leather padded inserts. Facing the driver was a special wood-rimmed steering wheel with three spokes, and a special "Grand Prix X-400" insignia in the horn button. The upper and lower dash was padded and a bank of three gauges, canted towards the driver, replaced the radio. On the left was an 8,000-rpm tachometer with a 5,500 redline. In the middle was a Judson-style supercharger boost pressure and vacuum gauge, and the righthand gauge was a clock.
A specially-built console housed a glovebox and a removable "Trans Portable" AM radio. Below that was a Muncie shifter that stirred a Warner T-10 four-speed manual transmission. Next to the shifter was another lever that controlled the loudness of the exhaust. It was a pet project of Pontiac Chief Engineer John DeLorean, and would eventually be known as the "Tiger Button." (This would eventually evolve into the short-lived vacuum operated exhaust option on the 1970 GTO.)
Under the hood was the new Pontiac 405hp 421ci engine, specially modified by Mickey Thompson with some of the same tricks he was using in his Pontiac land speed attempt vehicles. The chrome-trimmed 421 was topped by a 4-71 GMC blower with four 1954 Corvette Carter sidedraft carburetors. The quartet of Carters was fed cold air through the open hood grilles. The "Positive Displacement" GMC huffer was set at 5.5 lbs boost and produced enough grunt to power the 4,700-lb X-400 down the quarter-mile to the tune of 14.92 seconds at 97.82 mph with Mickey Thompson at the wheel. That was just the kind of go-fast that made Bill Mitchell a very happy executive.
 Under the hood, there's plenty...  Under the hood, there's plenty of chrome surrounding the new Pontiac 421. Sidedraft Carter carburetors fed the 4-71 GMC blower. |  Swing-up, chrome mesh stone...  Swing-up, chrome mesh stone guards protected the rectangular Cibie Marchal headlamps. Cibies were popular with customizers in the '60s, but were illegal on the street in all 50 states. Some things never change! |  The dual exhausts exited through...  The dual exhausts exited through twin ports located just ahead of the rear bumper. Note the concave, brushed-aluminum molding that ran from the mid door to the rear bumper wraparound. |
 The unique aluminum "eight-lug"...  The unique aluminum "eight-lug" wheels featured an integral hub and drum arrangement that was manufactured by Kelsey Hayes specifically for Pontiac. |  The Mickey Thompson-built,...  The Mickey Thompson-built, blown 421 produced enough horsepower to push the X-400 down the quarter in 14.92 seconds with a trap speed of 97.82 mph. |  The thin-shell bucket seats...  The thin-shell bucket seats were covered in red leather and the door panels featured brushed-aluminum panels trimmed with vertical red leather inserts. The carpeting, console, and dashpad were done in a matching shade of red. |
 All of the exterior emblems...  All of the exterior emblems and nameplates were removed except for the Grand Prix insignia located at the front of the side molding. |  A bank of three gauges replaced...  A bank of three gauges replaced the radio's unusual location. Canted towards the driver, the gauge cluster featured an 8,000-rpm tach on the left, supercharger boost and vacuum gauges in the center, and clock on the right. |  A handsome, thin-rimmed three-spoke...  A handsome, thin-rimmed three-spoke wood wheel with a "Grand Prix X-400" insignia in the Lucite horn cap was unique to the only convertible 1962 Grand Prix ever built. Next to the Muncie shifter is the lever to adjust the exhaust volume. |
 The radio was relocated to...  The radio was relocated to the specially built center console stack that integrated the floor shifter console to the instrument panel. |  The hood had been modified...  The hood had been modified with twin cold-air vents installed on either side of the hood centerline, and was not offered in production Grand Prix models. | |