THE BIRTH OF THE BUICK RIVIERA AND OLDSMOBILE XP-784
Although Cadillac had rejected the XP-715, the design was not yet dead. Since Buick, Oldsmobile, and Pontiac were all interested, GM held an internal competition in the fall of 1960 to determine who would build the car. The eventual winner, as we have previously seen, was Buick, and the LaSalle II became the 1963 Buick Riviera.
Well before the Riviera even went on sale, Oldsmobile was asking the corporation for a Riviera-style specialty car of its own. Around the spring of 1962, Car and Truck Group VP Ed Cole finally relented, authorizing the development of a new personal Olds for the 1966 model year. As we discussed in our Toronado history, it would be based on a rendering by Oldsmobile stylist Dave North, created as an exercise earlier that year. That fall, Advanced Styling Studio 3 developed North’s concept into a full-size clay, the XP-784. It would later become the 1966 Oldsmobile Toronado.
As Dave North originally conceived his “Flame Red Car,” it would have been the size of the later Chevrolet Camaro; Bill Mitchell later lobbied unsuccessfully to have it built on the A-body intermediate platform. The production Toronado was considerably bigger than either, stretching 211 inches (5,359 mm) on a 119-inch (3,023mm) wheelbase.
Dave Holls, Cadillac’s assistant chief stylist during this period, says the development of the Riviera and Toronado galvanized Bill Mitchell’s determination to build a sporty Cadillac personal car. If both Buick and Oldsmobile were to have stylish specialty cars, Mitchell argued, it hardly made sense for Cadillac to be left out.
The Cadillac studio had revived the XP-727 project in early 1961, resulting in a new full-size clay, the XP-727-2. We were unable to obtain pictures of that model for this article, but photos of it in other sources show a subtly V-shaped windshield, skirted rear wheels, peculiar headlamp ‘eyebrows,’ and broad semi-fastback sail panels. The XP-727-2 was apparently another dead end and was abandoned after August 1961.
As the Oldsmobile XP-784 took shape, the Cadillac studio developed another clay, the XP-727-3. It once again sported a V windshield, adding rear ‘suicide’ doors and another curious front-end treatment with exposed high beams and concealed low beams. By November 1962, that model had reached a highly finished state, but it was rejected as insufficiently modern-looking.
A full-size model of Cadillac’s four-door XP-727-3, photographed in late 1962. Note the very low beltline crease — accentuated on this model with bright trim — and round, flared wheel arches, which stylist Don Roper said were intended to emphasize the curvature of the body sides. According to Roper, Cadillac dropped this theme in favor of the squared-off wheelhouses of the XP-820 and XP-825 prototypes because Oldsmobile (or perhaps Advanced Studio 3) had already borrowed the flared-wheelhouse look for the Toronado. (Photo copyright 2010 General Motors LLC. Used with permission, GM Design.)
THE E-BODY CADILLAC
Full-size models of Oldsmobile’s XP-784 design were completed by February 1963 and received management approval in April. By that time, there was a strong possibility that it would have front-wheel drive, with which Oldsmobile had been experimenting since 1957.
The extent of Cadillac’s interest in front-wheel drive up to this point is unclear. Most of the enthusiasm for that idea appears to have come from Styling or the Engineering Staff rather than the division itself; the XP-727 (and possibly the XP-727-2 and -3) was designed to accept either front- or rear-wheel drive and some early examples of the experimental OHC Cadillac V-12 (described in the sidebar below) were intended for transverse installation, implying at least some tentative notion of using the V-12 in a FWD application. However, both the stylists and contemporary Oldsmobile employees, including former Olds comptroller Dick Elliott, later maintained that Cadillac management remained indifferent to the whole idea.
Harold Warner’s interest or disinterest in FWD would soon become a moot point. By mid-1962, Ed Cole had decided that in order to maximize the corporation’s return on the sizeable tooling costs of the new Oldsmobile personal car, Cadillac should have its own mechanically related car for 1966, sharing the corporate E-body shell with the Olds and the second-generation Riviera. Although formal approval for front-wheel drive would not follow for almost two more years, Cadillac was ordered to collaborate with Oldsmobile and Buick on the development of the FWD powertrain and platform.
Two versions of Cadillac’s XP-784. The finished two-door model, photographed on July 24, 1963 (top), appears to share the V-shaped windshield of the XP-727-3, but otherwise looks quite different, with a higher beltline and partially shrouded wheels. The headlight arrangement isn’t clear, but it may have been intended to use Sting Ray-like pop-up lights. The less-finished clay model (bottom), dated August 30, 1963, has what appears to be provision for rear suicide doors. Note the sail panel shape and the lack of vent windows, some of the few design elements that clearly resemble the eventual production car. (Both photos copyright 2010 General Motors LLC. Used with permission, GM Design.)
In May 1963, the Cadillac studio, now led by Stan Parker, developed a new clay model based on the package dimensions of Oldsmobile’s XP-784 and confusingly sharing the same designation. Cadillac’s XP-784 had little in common with the earlier XP-727 concepts except that it was initially also a two-door coupe; by August, however, this had been superseded by a four-door version, again with rear suicide doors. This, too, appears to have been a dead end and it was dropped by September.
After the demise of the XP-784, the Cadillac studio started over, leading to a new clay, the XP-820. Photos of that model suggest a return to the themes of the earlier XP-727-3, including a similarly low beltline molding and bladed fenders, which according to Stan Parker were originally suggested by Bill Mitchell. The XP-820 also added a number of new elements, including a V-shaped backlight and a curious concave windshield. There were studies of a possible convertible version, although the eventual production car would be offered only as a two-door hardtop.
The XP-820’s concave windshield and front fenders are obviously quite different from those of the earlier XP-727-3, but the low beltline crease and V-shaped prow are similar, as is the relationship between the sail panels and the rear fenders. This photo illustrates one of several headlamp treatments tried on the XP-820; this one would not have been legal in many U.S. states at the time. Note the boards in the background, depicting some of the multicylinder concept renderings the Cadillac studio produced during the same period. (Photo copyright 2010 General Motors LLC. Used with permission, GM Design.)
According to Automobile Quarterly, the XP-820 was based on the full-size C-body used by other Cadillacs rather than on the E-body shell. While the XP-820’s wheelbase does appear to be significantly longer than that of the E-cars, we have no explanation for why the Cadillac studio would have made such a change given the corporation’s apparent interest in maximizing its use of the E-body tooling. Note the wheel arches, which are still flared, but no longer rounded, like the earlier XP-727-3. (Photo copyright 2010 General Motors LLC. Used with permission, GM Design.)
SIDEBAR: A NEW SIXTEEN AND THE V-12 THAT WASN’T
Although Cadillac had offered both V-12 and V-16 engines during the brief thirties vogue for multicylinder luxury cars, the V-8 had been the division’s bread and butter since 1914. By the early sixties, however, V-8s had become ubiquitous. Some GM designers and engineers felt the division needed something with a little more kick — and a few more cylinders.
Around 1959, both the Cadillac styling studio and Bill Mitchell’s special projects studio (which created the design that became the first Buick Riviera) began playing with ideas for a modern Sixteen. Like GM’s Motorama dream cars, some of these designs were quite fanciful, blending thirties formal coachwork with race car velocity stacks and hoods the size of an aircraft carrier flight deck. (Gary Smith’s Dean’s Garage website has run pictures of a few of them, including a rendering by designer Wayne Kady that presages Kady’s later 1980 Seville.) A few reached the scale-model stage, but Chuck Jordan said later that none of them was really intended for production. There was at least one actual V-16 engine prototype, cobbled together from two V-8s, but it was apparently a just exercise with no serious engineering development.
To our knowledge, this car — XP-840, photographed circa December 1965 — was the only multicylinder Cadillac styling study to reach the full-size model stage during this era. According to David North, this car was done not by Cadillac, but in Ned Nichols’ special projects studio, with considerable input from Bill Mitchell himself. Not visible in this shot are the split windshield, V-shaped hood bulge, and bladed front fenders; to us, this design looks like the product of an illicit liaison between a Toronado and a Corvette Sting Ray. (Photo copyright 2010 General Motors LLC. Used with permission, GM Design.)
A new Twelve was a more serious production possibility. In the early sixties, Cadillac engineer Paul F. Keydel developed a sophisticated new V-12 for future Cadillacs, featuring chain-driven overhead camshafts and all-aluminum construction. Both the block and heads were die-cast, using a new “Acura-Rad’ process and a high-silicon alloy (like the later Chevrolet Vega engine) that would theoretically have obviated the need for cylinder liners. We don’t know the V-12’s bore and stroke dimensions, but author Karl Ludvigsen says it initially displaced about 450 cu. in. (7.4 L), later expanded to 500 cu. in. (8.2 L).
According to Ludvigsen, the early V-12 prototypes, built in 1962, were designed for transverse FWD applications. This was apparently just an experimental project, but at some point in 1963, Cadillac asked the corporate engineers to adapt the V-12 for longitudinal installation, which would have have facilitated using the V-12 in Cadillac’s RWD production cars or the FWD E-car. Former Cadillac engineer Dan Adams later said the Engineering Staff built five or six prototype engines in all, the last of which was completed by early 1964.
In 1981, Richard Langworth reported that the Cadillac V-12 had split crank pins like later editions of Buick’s 3,791 cc (231 cu. in.) V-6, leading him to conclude that the Cadillac engine also had a 90-degree bank angle; at the time, he had not actually seen the engine, since Cadillac declined to release photos of it. However, Karl Ludvigsen describes the V-12 as a 60-degree engine, which is what it looks like. If it did indeed have split crank pins as Langworth reported, we don’t know why! (Photo copyright 2010 General Motors LLC. Used with permission, GM Media Archive.)
The V-12 would have given the FWD Eldorado a clear advantage over the Toronado and Riviera, but if that idea was considered, it didn’t get very far. Although the corporate engineers experimented with various carburetion and fuel injection set-ups, the best output they were able to achieve was 394 horsepower (294 kW) and 506 lb-ft (683 N-m) of torque, underwhelming for an engine of the V-12’s size and complexity. The V-12 would undoubtedly have cost far more to build than a cast iron V-8 of comparable displacement and the viability of the Acura-Rad process was still uncertain. There were also concerns about the V-12’s ability to meet the new state and federal emissions standards then emerging. Prototype testing ended in April 1964, although rumors about the V-12 persisted in the automotive press for some years afterward. In a 2006 interview with Ron VanGelderen, Chuck Jordan insisted that there were never any serious plans to use the V-12 in the new Eldorado.
By the early eighties, Cadillac had become rather cagey about the V-12 program. When writer Richard Langworth was preparing an article about the engine for Special Interest Autos magazine, he found the division unwilling to even release photos of the V-12. However, one of the surviving prototypes is now on display at the GM Heritage Center in Warren, Michigan.