In March 1965 Bill Mitchell showed GM's upper management his new Mako Shark II design concept. After the attendees got their breath back, their first question was probably, "When can we have it?" Publicity photos were made, and the non-running Mako Shark II was shipped off to New York City for the 9th Annual International Automobile Show. From there it went to the World's Fair, also held in the Big Apple that year. Meanwhile, two orders were given: Build a running prototype, and begin work on a production version. Incredibly, GM management wanted the new design to debut as a '67 model. That meant there were only 18 months to develop the car.
A running Mako Shark II was shown to the press in October, then shipped off to the Paris Auto Show. The car used a 427 big-block and was festooned with every special feature imaginable. It was a classic GM Motorama–type dream machine designed to stoke the press and Corvette fans. Hot Rod magazine put the car on the cover of its December issue with the headline, "Is This The '67 Corvette?" Meanwhile, engineers and stylists discovered that translating the Mako Shark II into a mass-produced car that buyers could live with was a major challenge. By the time Larry Shinoda was promoted to Chief Designer at Chevrolet Studio 3 in April 1966, it was obvious that the project needed another year--or better yet, two. The new car used the existing Corvette's frame and running gear, so it seemed that designing the body and interior wouldn't take too long. Early clay studies used many of the Mako Shark II design elements, but aerodynamic problems quickly surfaced. A '65 Corvette only needed 155 horsepower to hit 120 mph, while the initial clay design needed 210 hp. It also experienced front-end lift at high speed. Although the nose of the car looked low, there was a lot air going under it. Plus, the sexy rear spoiler was pushing down on the back end, exacerbating the problem.
Then there was the issue of outward visibility. To help, the front fender humps were trimmed, the rear spoiler was reduced to a subtle lip, and the roof line was changed. The center beltline was then raised to maintain the front grille's proportions, and a slight air dam was installed. To reduce front-end lift, vents were added to the front fenders. New tests showed that only 105 hp were now needed to hit 120 mph, and that front lift had been reduced from 21?4 inches to just 5/8-inch. A coupe body style makes any vehicle more rigid, so a T-bar was added to the roof section to keep the car as stiff as possible, while still offering a quasi-convertible feature. The interior had its challenges, too, as the seats had a 33-degree angle, whereas the Sting Ray's seats were placed at a more upright 25-degree angle.
The car was completed for the 1968 release, but it wasn't really finished. Before the summer press preview, it was discovered that the big-block cars had an overheating problem. Duntov's quick fix involved cutting two slots ahead of the air dam and doubling the depth of the chin spoiler for increased radiator airflow. The cars still ran hot but didn't (usually) overheat. Compared with the Sting Ray, the new car was 100 pounds heavier, 7 inches longer, and 2 inches lower, while width remained the same. The stylists and designers were happy with the translation from show car to production car, even if the interior and trunk were smaller than envisioned.
The press preview went very well, but when production cars arrived, it wasn't pretty. Car and Driver tried to evaluate one for its Dec. '67 issue, but ended up canceling the test because the 2,000-mile press loaner was literally falling apart. Body panels were too loose or too tight, the fiberglass was wavy, doors and locks were stiff. There were rattles, water leaks, a loud resonance at idle, an overheating engine, and other problems--48 in total. Later, when the magazine tested an improved, 400hp 427 model, the writer commented, "A brilliant car with all the virtues and vices of an American car." Car Life said, "Who needs LSD with something like this to get high on?" It seemed that Motor Trend's "Sports Car of the Year" award was a little premature. Perhaps buyers didn't catch C&D's scathing initial review. The '68 model set a new Corvette sales record with 28,566 units sold--9,936 coupes and 18,630 convertibles. Had the '67 model been carried over another year to allow more time to groom the new car, it's unlikely that number would have been reached. Nevertheless, the accelerated design schedule used on the '68 edition was not something Chevrolet would try again.