Automotive History: The Opel GT. 1968-1973 – The Long Road From Inspiration To Production with Many Cooks Adding to the Broth Along The Way

Production Opel GT 1968-1973

(first posted 8/6/2018)       Sports car fever of the ’50s and ’60s infected enthusiasts, car designers, and car stylists alike on both sides of the Atlantic.  Like an arms race, successive sports car designs became more and more effective tools in racing and giving prestige to their companies with secondary prestige to the more mundane products.  Ford and Chevy would boast of the optional Thunderbird and Corvette engines in their sedans.

For General Motors starting with the 1953 (later known as the C1) Corvette there was relatively rapid engineering development via Zora Arkus Duntov’s urging and initiatives (v8’s, fuel injection, involvement in racing, etc).  Bill Mitchell, long a racing and sports car buff, promoted a similar rapid development of sports car styling themes with a who’s who list of styling greats, concurrently developing many interesting styling themes. Out of this fertile environment two new production sports cars first saw the light of day in 1968, the C3 Corvette and the Opel GT.

 

 

 

The 1957 magnesium bodied Corvette SuperSport XP64, its development quickly pushed through in 6 months by Zora Duntov, with aero drag similar to the Jaguar D-Type and a lightweight tubular frame patterned after the Mercedes 300SL.

Clare (“Mac”) MacKichan, Chief Designer of the Chevrolet Studio; Ed Donaldson, Chief designer of Chevrolet Interiors; Bob McLean, head of GM Styling Research Studios; and Joe Gilson of GM Styling reworked a model crafted by Zora A. Duntov into the concept for the XP64, as above.  Clare MacKichan was involved with many of Chevrolet’s key designs including the classic 1955-1957 Chevrolets and the Corvair.

 

 

… And simultaneously in 1956-57 in another design studio, also under the inspiration of Zora Arkus Duntov, who had worked out the entire basic layout for an all-new second-generation Corvette (with a target 1960 introduction) using a steel platform, independent front suspension, and a rear suspension based on a new transaxle with a modified swing-axle design, using universal joint half shafts as stress members–the 1957 Q-corvette with the winning design of 19 year old Peter Brock, aided by Chuck Pohlmann and Norm Neumann.

 

In 1959 Peter Bock’s design became the basis for Bill Mitchell’s Sting Ray Racer built upon the remaining Corvette Supersport XP64 mule chassis.

 

Later the Styling of Peter Brock’s Q-Corvette and Sting Ray Racer was reworked by Larry Shinoda into the styling of the production 1963 Corvette Sting Ray.

 

… And in the late 1950s,  the late Larry Shinoda and the late Tony Lapine while working in Bill Mitchell’s Secretive  Studio X workshop were developing the Corvair based Sebring Spyder, Super Spyder teasing the production Corvair.  Additionally Larry Shinoda and Tony Lapine (born in Riga, Latvia, later to lead the styling of Porsche’s 928) were involved in the styling development of the 1963 Corvette, the CERV I and Cerv II  mid engined Corvette prototypes, and Corvair based Monza SS and the mid engined Monza GT show cars which were engineered by Chevrolet’s Research and Development Department in 1962.

… And in 1962-1966, encouraged by Pontiac Chief Engineer/future Division Chief, John Zachary DeLorean, the XP-833 program began in August 1963 to assess and develop styling and suspension possibilities.  Initially four full sized mock-up cars were developed, SP 1 through SP4.  The initial SP1 engineering and design direction was co-ordinated by Dick Denzer by the Advanced Engineering Group.  The bodywork styling direction of SP1 was managed by Ned Nickles and Roger Hughet under the direction of Paul Gillan, the head of GM’s Advanced Design Studios I and II.

The SP1 was designed around the use of a prototype Pontiac OHC-6 engine undergoing development for production usage in the 1966 Pontiac A-body, to be in the Tempest and LeMans.

The SP-2 using a custom frame utilized a custom four-wheel independent suspension and modified C2 Corvette body panels.

The SP-3 used a modified C2 Corvette frame from a 1963 Corvette, with a non-production torque-tube drive line and oddly a Jaguar Independent Rear Suspension in place of the Corvette IRS.  A very odd design choice!

SP-4, was even more odd than SP-3 when it used a modified 1963 Studebaker Avanti Chassis!!

Then the Bombshell of the first series Mustang hit the developing “youth” market in April 1964, instantly seducing the American public with sales of more than 1,000 units per day in the initial months of sale, and by December 1965 Ford had built and sold 680,992 Mustangs.  GM claimed that the Corvair Monza was the natural Mustang competitor, but the massive Mustang sales volume had to be answered by a comparable GM competitor, the new F-car code-named the”Panther”.

Ironically John Z. Delorean , as Pontiac Chief Engineer, before becoming Pontiac General Manager, sought other car types to extend the Pontiac lineup.  One of these projects was XP-798, an “exotic” four seat GT car influenced by the Ferrari 2+2, Aston-Martin DB-5, and American engined European exotics like the Iso Rivolta and Gordon-Keeble.  This was well in keeping with GM’s tradition of cribbing from Europe’s best like Harley Earl’s 1920’s LaSalle which was deeply influenced by the Hispano Suiza.

Project XP-798, initially called the Scorpion, started in December 1962 at GM’s Advanced Studio I under the direction of Ned Nickles who expanded an earlier Pontiac Sports Coupe XP-788 into a four seat version, the XP-798.  When Chevrolet caught wind of the project, they signed on for a possible four place version of the Corvette, but by March 1963 Chevrolet quit the program.  The XP-798 was built on a 109 inch wheelbase, length of 196.7 inches, width of 69.8 inches, height of 49.8 inches,  a front mid-engine position of the 421 Pontiac V8, and with an IRS similar to Corvette and Jaguar design with unequal control arms and drive axles serving as the upper control arms.

 

 

1966 Pontiac XP-798 Concept 4 place Sport Coupe, rear 3/4 view.

The styling of the XP-798 was essentially a very stylized version of what became the long-hood, short tail deck proportions of the future 1967 F-cars, the Pontiac Firebird and the Chevrolet Camaro, a styling direction rapidly appropriated for the crash program development of the GM Mustang competitor.

Within GM, John Z Delorean was being pressured to join the F-body program.  John Z. Delorean had other ideas.  So much so that the construction of two functional two place cars, as fraternal twins, so to speak, the 1964 SP-5 Coupe and the 1964 SP-6 were done in secret.  The SP-5, a two place coupe, with the Pontiac SOHC  6 cylinder engine and the SP-6, a two place roadster, with a Pontiac WR-coded 326 HO V8. Forward hinged hoods with appropriate bulges would accomodate the engines used.  The smoothly rounded, tapered, forward central hood bulge of the SP-5 Coupe provided engine clearance for the front of the SOHC 6 ( a similar configuration bulge was used in the later Opel GT to clear the carburetor–good ideas never die, it seems).

These two functional, driveable prototypes economically engineered using multiple GM components already on parts shelves.  Visually the Coupe and the Roadster were stunning, especially for 1964, but still looking fresh and appealing.

 

Designer Jack Humbert, working secretly, influenced by the Corvair SS and the Corvair mid-engined Monza Coupe, developed the fiberglass bodied 1964 Banshee XP-833,  previewing upcoming GM designs with its long nose, haunching “coke bottle” profile, slender chromed bumpers, steeply raked A-pillar and windshield, a fastback roofline sweeping into a subtle spoiler accenting a truncated Kamm back tail light recess.

The size of the Banshee mirrored the future German  Opel GT.  Pontiac Engineer Bill Collins engineered a smaller lighter sports car using GM’s existing parts bins.   Then compared to the Corvette,  Collins eliminating the heavy metal ladder frame by placing the Banshee on a 90 inch wheelbase, same as the MG TD steel platform chassis, shorter, compared to the Corvette’s  98 in wheelbase.  He utilized a cost saving A-body coil spring, live rear axle suspension to be used on the 1964 Le Mans.

He prepared both a Fiberglass Coupe (SP-5) and a Fiberglass removable top convertible (SP-6) as prototypes. One, the SP-5, was engined for the Pontiac SOHC six cylinder head in 207/215 bph “sprint” state of tune, but in actuality, a milder production base Tempest version 1-barrel carburetor 167 bph version was installed.  The second Banshee, the SP-6, the roadster was designed to accommodate the Pontiac V8 engine family from the 326 c.i.d V8 to the H.O. 421 with a hydraulic clutch Muncie M-21- four speed in a car weighing approximately 2,615 lbs, approximately 500 lbs less than the Corvette Roadster.  The size was similar to the future Opel GT, though more weighty, but with an easily apparent, potential power-to-weight ratio better than the Corvette, especially if equipped with the H.O. 421.

 

 

 

The XP-833 Banshee chassis despite being non-production looked liked a shortened A-body chassis with a 90 inch wheelbase with many production A-body components in place.  Unlike the Corvette C3, or for that matter, even the Porsche 904, both of which had full frames with fiberglass bodies, the X833 had an essentially low, flat, belly pan appearing, steel floor pan with a steel cowl, steel rear inner wheel housings, as well as other needed steel structural supports/braces. The fiberglass body was bonded to the pan and with the supports to increase strength and rigidity improving upon the practice of the contemporary Lotus Elite where Lotus used Fiberglass for the load bearing structure of the car, and with a steel subframe for engine support.

Due to the need for complete secrecy of the Project XP-833, Delorean/Pontiac arranged for production of the bodies in Midland, Michigan, by Dow-Smith who arranged for a production read/production capable design with parting lines allowing easy lay-up of simple, large sections for easy alignment, assembly, and bonding.  The styling used curved flowing lines with bulging, creased fenders and wheel wells, doors with rear coke-bottle kick-ups seemingly flowing into the rear fenders.  It was a styling tour de force in 1964 resembling the still-in-the- future 1968 C3 Corvette but with different side treatments.

The rear of the XP-833 Banshee became the stylistic inspiration for the slotted tail lamp rear treatments of the production 1st and 2nd series Firebirds. The split chrome bumper grille became a trademark of early Firebirds, and then lived on in the Endura color matched grilles of the 2nd series.

The size of the XP-833 was recapitulated by the later Opel GT built on the Opel Kadett platform.  The rounded front pop-up headlamps of the XP-833 Banshee and those of the Opel GT are virtually identical, as well as the contours of the Opel’s hood bulge.

 

THE BANSHEE PROPOSAL TO GM’S UPPER MANAGEMENT.

In July 1965, Delorean was placed in charge of Pontiac.  In a move orchestrated by Delorean, XP-833,  Project Manager Bill Collins made an elaborate illustrated, glossy well researched presentation to GM President James Roche and others of GM’s upper Executive Management detailing that a sub $3,000 market existed for a two seat Pontiac to compete with British sports cars like the Triumph TR-4, MGB, and Austin Healey, and the smaller $2,000 MG Midget and Triumph Spitfire.  The study projected potential sales volume of about 32,000 yearly sales at a projected 1967 price of $2,500, total development cost of approximately $15-18 million, with substantial cost savings by using existing GM parts bin componentry.

The presentation of two assembled, driveable, fully functional prototypes shocked and surprised everyone.  Even Bill Mitchell, GM’s Head of Styling, who had been invited to the viewing, was surprised at the unveiling of two fully styled, driveable, previously secret prototypes.  The secret had been complete, limited only to Delorean’s Inner Circle, until the viewing.

The Collins Proposal was rejected.  The higher priced Corvette sold at a rate of approximately 20,000 per year.  It was felt by GM’s 14th Floor Management that the XP-833/Banshee would steal sales from the Corvette.  Therefore a predictable GM board decision shelved John Z. Delorean’s dream of a Pontiac two seat sports car by fully anticipating that the Banshee would be an in -house Corvette competitor.

 

MEMO OF DIRECTION TO BILL MITCHELL.

The GM Executive Committee instructed DeLorean to end further development of the XP-833/Banshee.  Then Bill Mitchell received an Executive Committee memo instructing Mitchell to have his staff proceed with updates of the XP-833 exterior clay and interior styling bucks “reflecting a Chevrolet design for the two-passenger version coupe”.  Because no good idea styling ideas should be discarded,  many of the Banshee styling cues were essentially resurrected, transferred, expanded, revised, and transformed by Bill Mitchell’s Chevrolet staff into the 1965 Mako Shark II concept which flowed evolutionarily toward the 1968 C3–the third generation of the Corvette.  Similarly front end themes developed for the XP-833, especially the rounded pop-up headlights and the comely hood bulge were freely incorporated into the production Opel GT

 

 

The major revision of the Banshee themes into the 1965 Mako Shark II concept would ultimately influence both the C3 and the Opel GT which were being simultaneously, continually revised to what became the final production C3 and Opel GT.

 

It has been said that the Banshee Roadster remains fresh, youthful even after 50+ years.  The Corvair SS, Corvair mid -engined coupe, the XP-833 Banshee influenced the Mako Shark II with similarities, and even divergences, occurring due to the multiple GM designers developing similar evolutionary themes flowing simultaneously under Mitchell’s ultimate direction into the production C3 and Opel GT models.

 

 

Regarding the GT, even Mac didn’t finalize the final production design, but that task fell to Chuck Jordan who replaced Mac in 1967. Jordan was one of the many cooks tending the final flavoring of the GT broth. Jordan was responsible for the final production GT contouring altering roof line elevation.

 

EVENTS IN GERMANY.

On March 10, 1962, on Clare MacKichan’s birthday, Bill Mitchell reassigned Mac for a promised five year only German stay as he was now chosen to modernize Opel’s then rudimentary, provincial styling studio in Russelsheim, to change its image, and to make the Opel, in the words of Chuck Jordan, “less of a German farmer’s car.”  Mac supervised the construction and fourfold expansion of the Opel Design Building.  While there he saw that “Sports Car Fever” was a worldwide phenomenon seeing that on his German staff a young German designer, Erhard Schnell (born 1927, Frankfurt), had been producing handsome, well crafted sports car designs. Working with Schnell was a similarly enthusiastic Opel designer, Mourad Nasr.

Starting in Autumn,1962, under Mac’s direction and urging, Schnell and his small group in the advanced design studio began generating clay and fiberglass models aimed at producing a future production sports car coupe.  The direction of the work was to produce a sports car with a distinctly German look, a look not yet influenced by the later American themes of the actual production GT.  Encouraged by Mac, the work was done in secret (much like DeLorean’s secret XP-833 project) away from the gaze of the conservative Opel middle and upper management who were as shocked as was the public during the Frankfurt Motor Show concept presentation in September 1965 at the audacity of Opel attempting to envision a sports car.  Because this was a German project, the performance parameters of the earlier Porsche 356 and the new Porsche 911 ( and especially the subsequent, when introduced, less expensive 912) were performance goals for any production Opel sports coupe intended for the German market.

 

 

The concept car was a stunner, an unexpected surprise,  for the German audience and for the Opel Management, but not so much of a stunner, or a surprise for GM Chairman Fred Donner, GM’s Overseas Chairman, Bunkie Knudsen, and Bill Mitchell attending the show who, especially Mitchell, were aware of the then current styling directions at GM America and being simultaneously encouraged in Germany by Mac.  Bob Lutz, then a lower level Opel marketing official, was pleasantly pleased, not shocked, by Mac and Schnell’s secret project when he was let in on the secret.    After he was aware of the secret project, Lutz had urged Opel to put the car on display at the ’65 Frankfurt Motor Show.  Lutz also commented that the concept Opel Sports Coupe was “more German looking, wider and flatter, something that Porsche would have done”,  without the peaked Banshee or later Corvette C3 swollen front fenders.

Active production was urged by Donner, Knudsen, and Mitchell to Opel’s shocked, even disbelieving, Upper Management who felt that Opel didn’t do sports cars, and that the sports car niche belonged to Porsche and Mercedes already.  Mitchell urged and recommended to Mac and Schnell that the production GT be more Americanized since he rightly felt that most GT’s would be sold in the US,  as it turned out by Buick dealers.

 

Mitchell instructed MacKichan to start looking at the styling themes and cues that had been developed for the Corvair Monza SS roadster and the Monza GT coupe, first developed and shown in 1962.

After the project was given the green light, a decision was made for production in late 1968. The Opel Engineering group recommended the existing Opel Kadett platform/chassis. the existing OHV 1.1 liter four cylinder engine, and that the Opel 1.9 liter Cam-in-Head from the Opel Rekord be the basis for the production vehicle

MIKE LAMM’s Thoughts on the OPEL GT:  In the “Opel GT.com” forum, in his 10-03-2014 post, Automotive writer Mike Lamm related that he himself had recently bought “a pristine, one-owner ’70 Opel GT” and had related that he had interviewed MacKichan several times before Mac had passed away in 1996.  Additionally Mike Lamm had email contact with Bob Lutz and posted some of Lutz’s comments and information learned from MacKichan as follows:

“As I continued my preliminary research, the question became:  Did one car (Corvette vs Opel GT, sic) exert an influence on the other?  And, if so, which lent its lines to which?  Was the GT truly a “baby Corvette,” or did the C3 come about as a larger version of the Opel–a GT on steroids?”

“One misconception I frequently ran into was the recurring contention that Corvette designer Lary Shinoda was the man behind the GT’s final design.  I soon discovered this was certainly not the case; Shinoda, whatever his role in shaping Corvettes over the years, had nothing to do with the GT.”

“Both Monzas (Corvair Monza SS and the Corvair Monza mid engined GT, and the Banshee, sic) pointed the styling direction Mitchell already had in mind for the 1967 (later moved back to ’68) C3 Corvette.  Now he, Mitchell, wanted to expand their example to the new Opel GT.  Mitchell also called MacKichan’s attention to the Mako Shark II concept which was seen in public to rave reviews in April of 1965 ( a year after the Banshee XP833 of 1964, sic), five months before the Opel show car’s Frankfurt debut.

 

 

While the Mako Shark II did contain all the key styling elements of the third generation Corvette, at the time Mitchell was guiding MacKichan, no productionized version of the Chevrolet had been penned.”

“To GM Design, the twin Monzas, Mako II, and the 1965 Opel GT were still a series of showcars.  According to Ed Taylor, a retired GM designer, who had become MacKichan’s assistant at Opel in 1965 (George Gallion and Tony Lapine also joined Opel’s design team around that time), Mac’s routine was to talk with Mitchell once a week on the telephone.  Mac would also send notes and photographs to his boss, Mitchell, on a regular basis, and these images arrived as the design of the C3 continued to evolve in Michigan.”

 

THE AMERICANIZATION OF EMILY,  the Americanization of the Opel GT, if you would, so to speak.

“As a result, both cars–the GT and the C3–developed pretty much simultaneously from the same stylistic DNA.  That said, one of Ed Taylor’s particular assignments was to “Americanize” the GT–to make it more like the upcoming C3 in detail.  He did this by lifting the knife edges of the front fenders and refining details such as the parking lamps and bumpers.  These modifications were minor, however, compared to the general proportions and themes which evolved on the cars independently.”

“In his email, Bob Lutz goes on that, “For cost and investment reasons, we based the production Opel GT on a modified Kadett platform, which caused, for me,the car’s most significant shortfall:  track too narow and wheels too far inboard.  At any rate, once we were headed for production, Mac, as he did with everything, had to airmail weekly progress photos to Bill Mitchell.  These would come back all marked up.”

“Lutz continued, “It was during this transition to a production version that the car started acquiring a strong visual resemblance to the C3, son of Mako Shark II, one of Mitchell’s favorites……. So, while the GT was neither precursor nor follower of the C3, both were driven by the common vision of the Mako Skark II, with Bill Mitchell acting as long-distance puppetmaster.”

“Lutz also had a good deal to do with the production GT’s handling and chassis refinement.  Opel’s own engineers and beancounters wanted to use the Kadett platform unchanged, meaning the engine would rest directly over the front-axle centerline.  Erhard Schnell, in his 1965  GT show car, had set the engine back nearly 16 inches to allow more horizontal taper to the front end.”

“Leaving the Kadett engine forward would not only spoil the GT’s proportions but would also result in nose heaviness and inferior handling. So Lutz and MacKichan had two Kadett mules built, one with the engine in the stock position and the other with it set back 16 inches.  Lutz then invited Porsche test driver Hans Herrmann and champion racer Eberhard Mahle to evaluate the two cars, and both decided that the set-back mule worked best.  The engineers agreed to build the production GT that way, relocating its engine 15.75 inches behind the axle line.”

“By the way,” Lutz continued. “French racing ace Henri Greder later modified some GT’s with suspension kits, lowering them about two inches.  Greder also modified wheel offset to achieve about two inches of additional track width.  That coupled with period wide rubber, completely transformed the proportions of the car, lending great body-chassis relationship to what was, heretofore, merely a superbly surfaced body sitting on what appeared to be a skimpy chassis.”

“The production GT design was finished under Chuck Jordan (previously instrumental in the 1958 Corvette redesign), whom Mitchell sent to Opel in ’67 to relieve Clare MacKichan after 5 years, as promised.  Jordan subsequently designed the handsome, highly successful Opel Record II and the Manta Coupes.  Beyond that, he and George Gallion also conceived the Aero Opel GT, a jauntily restyled targa derivative with a removable roof, electric backlight, and Ferrari Dino-like flying buttresses.  Opel built two Aero GTs for the ’69 European show circuit.  George Gallion eventually bought one of them and, at last report, had put over 20,000 miles on it.”

“Getting back to the GT/C3 question, I think (Lutz’s comments) it’s fair to say that neither car influenced the other as much as both came from common ancestors–most notably the two Monza concepts and the Mako Shark II.  Chuck Jordan summed up the relationship for me with these words:  “I don’t think the Opel guys influenced the Detroit designers at all, in any way.  The Detroit people looked down their noses at us Opel designers.  I can say that, because I worked in both places.  Opel was GM’s country cousin.  Mitchell would come over and pat us on the head and go have dinner with us, but I can’t think of any influence that flowed back into Corvettes from the Opel GT.” Yet if information flowed the opposite way, Jordan concludes, it was likely due to MacKichan’s  “….intimate relationship with the marque,” not to direct interference from Detroit.  “[Mac] had really strong feelings for Corvettes.  He loved to go watch them race at Elkhart… He was just nuts for those cars.  That probably had as much as anything to do with where that look came from.”

 

Interestingly, in Germany and other parts of Europe, the styling of the production Opel GT was criticized for not being “as pristine or pure as the prototype” of the more European tastes evident in the original 1965 Frankfurt Concept show car.

In the USA, Road & Track Magazine criticized the new 1968 C3 Stingray for retaining the IRS ladder frame which had debuted in 1963, for its larger dimensions, and its for increased weight at 3300 lbs.  (note: 3300 lbs in 2018 doesn’t seem excessive when the 2018 Honda Accord weighs between 3150 to 3500 lbs,  the 2018 Corvette weighs 3,298 to 3582 lbs, and the 2018 Porsche 911 weighs 3142 to 3682 lbs).

In reality, despite some media criticisms, both cars were equally successful in the marketplace, complementing each other in their different market niches, and not competing with each other.  In effect the relationship of the Opel GT to the Corvette was similar to the healthy, complementary market niche relationship of the Mercedes 300SL with the less expensive, less powerful, less prestigious Mercedes 190SL.

 

 

Enjoy reading the following two articles about the Opel GT.  The second has some English captions but is predominantly written in German.

This following OPEL GT, article by Jerry Sloniger, author, was originally published in Automobile Quarterly, Second Quarter 1986,  XXIV, Volume Number 2, pages 212-221.

 

Booklet:  Opel GT Coupe’

Vom Sportcoupe’ zum Liebhaberfahrzeug

Redaktion:  Stefan Knittel. Text: H.J.Klersy.

Mitarbeit und Fotodokumentation: Adam Opel AG, Opel GT-Club, Jerrold Sloniger, S.Tiefenbach

Englische Texte:  The Slonigers

This booklet was reproduced in its entirety, and with additional inserts, with thanks and appreciation, as follows: