Why aren’t 1968-73 Opel GTs worth more?

1968 Opel GT ad

The elegant Opel GT coupe was introduced as a concept at the 1965 Frankfurt and Paris Motor Shows and widely hailed in Europe as a mini Corvette. Opel was GM’s European satellite, and the GT’s origins were definitely entangled with the redesigned 1968 C3 Corvette; both shared styling cues from the 1965 Mako Shark II.

But the small size of the Opel GT and its modest performance (by American standards) resulted in the attractive sports coupe being tagged in the U.S. as a vehicle better suited for females—something the Mazda Miata had to overcome in the early 1990s. In addition, GM foisted the captive import on Buick dealers, whose customers must have been mystified.

But the Opel GT’s pedigree was genuine, and some heavy hitters from Detroit were involved from the beginning. They included Clare MacKichan, who designed the iconic ’55 Chevrolet and was Opel’s chief of design from 1962–67, and Chuck Jordan, who would become GM’s vice president of design.

The GT’s underpinnings came from the lowly Kadett, but the design was executed with finesse, and bodies were built by Brissonneau and Lotz in Paris. The GT was launched in 1968 with a 60-bhp, 1100cc, OHV four-cylinder engine, and the 1897cc “high-cam” engine, which developed 90 bhp and gave quite a bit more performance. In all, 103,373 GTs were built, with about 70,000 coming to the U.S. Only 3,573 were fitted with the 1100cc engine, but they were not sold in America.

1971 Opel GT advertisement
1968 Opel GT

The GT’s layout was conventional, with transverse-leaf independent front suspension and live rear axle located by coil springs, trailing arms, and Panhard rod. Brakes were disc/drum and steering rack-and-pinion. The engine was set far back for a 54/46 percent weight balance. Hidden headlights were operated manually with a console-mounted lever, and both flipped over sideways. There were four round taillights at the rear but no opening trunk, to maintain structural rigidity. The exhaust led back to a laterally mounted muffler with dual tailpipes, and while it seems clunky, the location enabled the exhaust to be raised and nobody has developed a better arrangement.

Visibility was good, despite the car being low; the front seats were comfortable and there was a fair amount of space in the tail, where the spare wheel and jack were concealed behind a vinyl curtain. The dash resembled the C3 Corvette, but the Opel had a set of cool rocker switches, which the Corvette did not.

Though a 128-bhp engine was proposed at first, the eventual motor delivered 90 bhp. Road & Track reported 10.8 seconds for 0–96 kph (0–60 mph), but wind-tunnel research at the University of Stuttgart, coupled with a ram-air intake for the Solex 32/32 carburetor, produced a claimed 115-mph top speed (and I’ve seen 128 mph from a stock car). Handling is generally neutral, though larger tires can reduce understeer. However lateral G’s vary quite a bit from left to right with only the driver in place.

The bash-bumper laws of 1974 doomed the Opel GT, which was fragile at best. Coupled with the frightening propensity for rust in the bodies, and the frustration of difficult access to the trunk, the cars fell out of favor as practical transportation.

In addition, some drastic mechanical weaknesses became apparent: The 1.9-liter engine had a tiny three-quart sump, so oil levels had to be checked regularly. The “flip-over” hidden headlights demanded that the wiring harness be exceptionally flexible. Once engine heat had hardened the plastic insulation, resulting cracks could lead to fires. Electronic ignition is a recommended upgrade, as the 1.9-liter engine is hard on points. Beware of a Weber carburetor upgrade, which is all-too common. While it improves 0-60 mph performance, the ram-air intake does not fit, with a corresponding loss of top speed.

Perhaps as part of the Buick marketing program, a number of Opel GTs were fitted with a pathetic three-speed automatic transmission. Many of the best survivors are so equipped, and it’s worth retrofitting a manual four-speed, or even a ZF five-speed. All Opel GTs are left-hand drive and there was only one convertible Aero GT built as a show car in 1969. A few 1100cc models sneaked in from Canada, and the engine is reported to be unburstable, with gas mileage in the mid-40s attainable.

1968 Opel GT advertisement
1970 Opel GT advertisement

Every obscure model with this much charm has a patron saint, so try the Opel GT Source in Sonora, Calif., which also reproduces hard-to-find parts like taillight lenses.

With such a large production figure, even though attrition has been severe, spares do exist. In a strange quirk, both wrecking yards and individual hoarders seem reluctant to crush parts cars. While sound cars may be increasingly difficult to find—like Citroen DS 19s—donor cars do exist. Eventually the combination of reasonable performance, evident grace, and the sheer rarity of seeing a GT on the road is bound to pay dividends.

At present, Hagerty values a GT in #1 (concours) condition at a reassuring $26,300, although most cars are likely to rate between #3 (good) at $8,300 and #4 (fair) for $3,600, which offers a comforting upside for an enthusiastic restorer. A #2 (excellent) is reckoned at $16,400; best to start with a sound driver and avoid projects.

For increased performance, the later 2.5-liter Manta engine had Bosch fuel injection in 1975 and is an easy transplant. There was even a Turbo Manta sold in the UK. Stoking the fires further, check out Virgilio Conrero’s race record with Opel GTs in the early 1970s. Conrero had been tuning Alfa Romeo 1300cc and 1600cc coupes and dominating his classes in Italy, so GM asked him to try his hand at the Opel GT. Conrero punched out the engine to 2.0 liters, increased compression to 11:1, and fitted two Weber 45 DCOE carburetors.

With a racing exhaust, power jumped to 190 bhp, 0-60 mph dropped to six seconds, and the quarter mile was cut to 15 seconds at 150 mph. Top speed was somewhere north of 170 mph. By the time Conrero had finished with the suspension and flares, his baby Corvette won the GT 2.0-liter class at the 1970 Targa Florio and came in ninth overall.  If you get the tuning bug, check out Conrero’s website.