Why aren’t Chevrolet Cosworth-Vegas worth more?

The fate of the Chevrolet Cosworth Vega can be compared to the DeLorean DMC-12’s. Appropriate since John Z. DeLorean created them both. Both underperformed when launched, but technology has advanced since their introduction and they can lay claim to their original intent.

Most DMCs languished for years as low-mileage curiosities in the $20,000-$30,000 range. However, they can now be affordably (relatively) modified into DeLorean’s original supercar dream. Besides, who doesn’t want to be Marty McFly, and disappear at will?

A similar future awaits the Chevy Cosworth Vega. It’s a link between John DeLorean’s 1964 Pontiac LeMans GTO, which also turned a modest mid-size coupe into a muscle car, and the wholly original 1981 DMC-12. John considered the same GTO approach with the Chevrolet Vega GT, which was an attractive subcompact coupe, resembling the 1970½ Camaro. While the Vega was more attractive than the stub-ugly Ford Pinto, 90 bhp was hardly GT territory when you could still buy a Chevelle SS 454.

The Vega desperately needed an injection of inspiration. The world’s first all-aluminum block engine was proving to be a failure. Developed by GM and Reynolds Aluminum, the block was cast from a high-silicon content alloy. Initial testing showed that it eroded like steel, but wear accelerated rapidly after 40,000 miles.

As a result, DeLorean, while Chevy’s general manager, approached Keith Duckworth of the UK’s Cosworth Engineering to design a full-race Vega motor, with a view to capturing the SCCA “B” Production class and Europe’s 2-liter sports car class. Duckworth was initially enthused, and developed a double-overhead cam head that could produce 290 bhp at 9,000 rpm. The so-called “TC” engine relied on twin 40 DCOE Weber side-draft carburetors and 1,000 would be built for homologation. On paper it looked to have an edge over the BMW 2002 and Alfa Romeo GTA.

However the Cosworth tuning package stretched the Vega block’s limits and the 12:1 compression ratio caused it to crack at the bottom. Duckworth gave up, and John DeLorean considered how best to use the motor. The answer appeared to be to dial it down for street use, as the Weber carburetors would not pass emissions.  Fuel injection seemed to the answer, but GM’s Rochester Division wanted control over the entire project, including catalytic converters, so Bendix was hired. GM engineers improved the engine blocks, and the twin cam was aimed at the 1974 model year. An alloy V8 was briefly tested, as was a Wankel rotary, but neither reached production.

Unfortunately for Mr. DeLorean, emission regulations were tightened for 1974, and the motor was significantly detuned. While 290 bhp would have been spectacular, reducing compression from 12:1 to 8.5:1 cut power to a measly 110 bhp. Additionally, the TC engine failed its EPA test with burned valves, and the production date slipped back to 1975.

DeLorean initially planned for the TC Vega to be silver with a black interior, but changed his mind and all 1975 Cosworth-Vegas were black with gold trim. The color scheme was unique to the Cozzie, which at $5,916 cost double what a standard Vega did and was the second most expensive Chevrolet model that year.

For the extra money, Cosworth Vega buyers got a fuel-injected, 16-valve, double-overhead cam engine, hand-built at the Tonawanda, N.Y., plant. It was reduced to 2-liters for racing purposes, and developed 120 bhp at 5,200 rpm, delivered through a four-speed gearbox. The chassis had a heavy-duty suspension with front and rear sway bars, and unique gold mag wheels with radial tires. Most interiors were black and the fully instrumented gold dash was engine-turned, with a numbered plaque.

Chevrolet’s target was 5,000 sales but only 2,061 units were sold in 1975. Marketing stepped up in 1976 and seven other colors were available. The grille now housed three bars with integrated turn signals, and the taillights were larger. A five-speed manual gearbox was optional.

None of that mattered. Sales declined to 1,447, in 1976, leaving 1,492 surplus engines. These sat around until the mid-1980s when 500 were dismantled for parts, and the remainder scrapped as a tax write-off.

Currently, Cosworth-Vegas seem like ideal candidates for appreciation. The best examples still bring only about $2,500 more than their MSRP, (though a 300-mile dark green metallic example brought $25,480 at a Florida auction in April 2016). The Cos-Veg attracted a small but dedicated group of enthusiasts and, like DMCs, low-mileage examples are not uncommon. You’re unlikely to find car with chronic rust issues, as most were garaged. However, Vega rust can be catastrophic, and such cars are best used for parts.

Two factors add considerably to their appeal. One is that the cars are now old enough to be eligible for special interest plates, to which they are legitimately entitled and can sidestep emissions issues (apart from California). The second is that engine management systems are far more effective now, so that a creative engineer has a fair chance at Chevy’s original 290 bhp target. At the very least, the Weber side-draft carburetor option guarantees maximum bang for the buck, with minimum complications.

The search for a clean original Cosworth Vega should probably begin with the owners club. Some of the 1976 colors are quite rare, but so far no accurate numbers have been compiled beyond club estimates.