The Citation is a running prototype based on J-car mechanicals, with fiberglass body.
An exercise in aerodynamics and efficiency
Chevrolet introduced its first front-wheel-drive car under the Citation name in 1979, as a 1980 model. Initially, it was a tremendous sales success but within a few years the segment had grown more competitive and more crowded with rivals from other countries, Japan in particular. The Citation, which started being developed in the mid-1970s, was aging.
Essentially visually unaltered from the original introduced back in 1979, the 1984 line-up was renamed Citation II after receiving some minor mechanical updates.
That same year, whether out of genuine aspirations for the model or merely to boost its name, Chevrolet engineers showed off their rendition of what a future Citation IV might be like.
At the time, former Chevrolet general manager Robert Stempel stated, “We think of today’s Citation II as a second-generation, front-drive Chevy. Assuming it will be followed in a few years by Citation III, then a car like the IV could be in line for production by the beginning of the [1990s].” Chevrolet ended production of the Citation nameplate after 1985 never having made a III, let alone IV.
Despite the demise of the production Citation, some of the Citation IV concept’s visionary ideas carried over to other production vehicles. However, before delving deep into specifics, please allow me to set the tone so we can better appreciate the decades-old technology.
Understanding the Times
In 1984, the movie Ghostbusters had just been released, and a ticket to see it only cost about $2.50. Bruce Springsteen’s Born in the U.S.A. not only debuted, but was also offered on the first CD to be made in the U.S.
In the budding computing arena, a new digital storage medium had just arrived: the 3.5-inch floppy disk; of course, many had yet to determine how to save anything to one using Microsoft’s new DOS 3.0. Interestingly, 1984 was the same year that Apple released its intuitive, mouse-controlled Macintosh home computer.
All of the aforementioned historical tidbits serve as colorful reminders of life during that time. However, what they don’t tell us is what contemporaries anticipated from the future.
From Art Deco to the Box
Since the days when art deco shapes were all the rage, stream lining became an important ingredient in automotive design. Apart from aerodynamic advantages, the decreasingly blunt shapes imparted refinement and progress, and even a hint of tomorrow’s world. From locomotives to rocket ships, it seemed designers sought to continually improve the aerodynamics of their cars without neglecting style.
During the sixties, tidier styles took over with crisper but overall sleeker lines. Although most designs out of the seventies rounded off the edges, the cars were still large with sometimes flamboyant and overwrought design traits which looked less than wind-cheating.
By the eighties, down-sizing was in and many manufacturers had adopted very angular, boxy designs for their mainstream products.
Despite generally occupying less square footage than their predecessors, their shapes still had plenty of room for aerodynamic improvement.
In the early eighties, Chevrolet engineers had estimated that the aerodynamic drag of contemporary cars, traveling at a speed of 50 mph, constituted 50% of the vehicle’s rolling resistance. Despite technological advances, it was almost as if the engineers and designers of that generation had given in to the wind.
What wasn’t widely known was that, at their Tech Center located in Warren, Michigan, GM had already fortified their heavy artillery and declared an all-out war against wind drag.
In August of 1980, GM’s engineers got a new tool, a big one: their Aerodynamics Laboratory. With its new on-site wind tunnel test equipment, GM’s Tech Center was well equipped to better understand how to cheat the wind, allowing them to move beyond the constraints of testing scaled models and outsourcing the work.
The tunnel’s testing area, which can experience steady, fluid-like wind speeds of up to 160 mph, is 70 feet long by almost 35 feet wide. Its 4,500-horsepower electric motor-driven fan measures 43 feet in diameter. With over three decades under its belt, the title for world’s largest wind tunnel (specific to automotive testing) still goes to this unit at GM’s Aerodynamics Laboratory.
The proverbial gloves were off and it would begin to show in GM’s forthcoming concepts.
The Product of Good Stock
The Citation IV didn’t show up on the concept scene entirely fresh. In fact, it is essentially a functioning clone of one its progenitors.
Its roots are arguably grounded in at least three concept cars that preceded it, all of which were released not with Chevrolet bowties but rather the General Motors name. Starting in 1981, the “Aero X
” was introduced, followed by the “Aero 2000
″ in 1982, and the “Aero 2002
″ in 1983. Each of these concepts was a full-sized model but not drivable.
Although the Citation IV’s shape is merely hinted at in the four-door Aero X, and the two aren’t likely to be confused, they do share certain traits. For example, flush glass and door handles, a grill-less front with under-the-bumper air inlets for engine cooling, and wheels positioned outward, flush with the body panels. Those forward-thinking features and more would be passed along to the Citation IV.
The Aero 2000 eliminated outside mirrors and any indication that windshield wipers were intended. Although the Aero 2000 employed pop-up headlights like the Aero X, the Aero 2000’s nose was more rounded and its windshield more swept back, clearly influencing the Citation IV’s design. The Aero 2000’s interior, while proposing some questionable ideas, also began to point towards Citation IV with slim-design seating and digital instrumentation that included a cutting edge heads-up display.
It’s in the Aero 2002 that the Citation IV’s family ties can be clearly be seen. The Aero 2002 incorporated what would sometimes be referred to on the Citation IV as a “beaver tail” rear end. While possibly not visually appealing to some, the design feature was critical in reducing turbulence at the car’s trailing edge. Like the Aero 2000 before it, the Aero 2002 was still designed with pop-up headlights in mind and used wheel skirts that covered nearly half of all four openings. One of the few visual differences from the Citation IV were the body-colored vents on top of the hood apparently intended to offer air extraction from the engine compartment.
Through testing in wind tunnels, engineers would determine a car’s Cd value which is a measurement of a shape’s resistance to air (lower values are better). Interesting design aside, the Aero 2002’s claim to fame would have to be its 0.14 Cd. This was a new record for GM designers for a vehicle of that size.
Putting Things In Perspective
How does the Aero 2002 concept’s 0.14 Cd compare to modern day aerodynamic designs? For comparison, running an ultra-efficient Chevrolet Volt through the wind tunnel will net a 0.28 Cd, twice as much resistance. How about a modern (C6) Corvette? Also rated at 0.28 Cd, in its most slippery guise.
In Volt’s and Corvette’s defense, they are production vehicles and the Aero 2002 didn’t even have an engine–meaning, it was designed with few engineering constraints. Further, there are other factors that affect aerodynamics besides shape-specific Cd ratings (for example, the size of the vehicle). Generally speaking, however, the Aero 2002 was and still is an incredibly low-drag design.
What A Difference A Bowtie Makes
On display for over a year at Disney World’s future-inspired EPCOT Center (known now simply as Epcot), GM’s series of non-running Aero concepts were little more than theoretical studies in aerodynamics for the engineers, and props for theme park tourists to gaze at. That is, until 1984 when engineers from one of its divisions set out to change that.
Enter the 1984 Chevrolet Citation IV concept. At first glance, there appears to be little changed from its GM-badged predecessor. With regard to its exterior shape, that’s an accurate assessment. However, it’s under the red fiberglass skin and behind the tinted glass where the significant differences reside.
Under Chevrolet, the Aero 2002’s spirit was transformed into a fully functioning car. The task was anything but ordinary since the shape had been dictated by the wind, not conventional engineering practices.
Since the GM-badged Aero 2002 lacked components essential for motoring such as outside mirrors, windshield wipers, and trifle things like a drivetrain and functional interior, engineers had their work cut out for them. And they were to be confronted with new challenges as a result of the unconventional design. The task was accomplished using not only customized approaches and unique technologies but also several borrowed parts; however, not from its namesake.
From Clay Shell to Customized Concept
To start, drivetrain engineers looked to GM’s then-recently introduced J-platform. (The J-platform was one of GM’s small, FWD offerings introduced for the 1982 model year and sold through the Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac divisions. The red one pictured to the left is a 1984 Chevrolet Cavalier convertible.) Notable portions donated to the concept from the J-platform were brakes and rear suspension.
The Citation IV’s front brakes were 9.7 x 0.5-inch discs, while the rear employed 7.9 x 1.8-inch cast-iron drums. Braking power was boosted by a newly developed Delco electric pump, in an effort to save space.
The aft suspension was a transverse beam with trailing arms, on (conical progressive rate) coil springs, with incorporated stabilizer bar.
The front suspension, was somewhat more unique. Non-standard engine and drivetrain positioning dictated Citation IV’s short-/long-arm (SLA) geometry front suspension borrow yet again from another production Chevrolet vehicle. This time, it wasn’t a direct swap and it wasn’t from a lowly compact.
Engineers used a transversely-mounted, modified version of the Corvette’s unique single-leaf, fiberglass composite spring. Suspension components and connection points were specific to the concept’s needs, as were the tunable large-rear/small-front control arm bushings.
The rack-and-pinion power steering system could be considered advanced for the time in that it was electrically (rather than hydraulically) assisted. This, as with the electric brake pump, was done in order to save space but also contributed to efficiency by replacing the engine-driven hydraulic pump with one driven by a DC motor, separate from the one used for the brakes. The amount of steering boost was variable, depending on vehicle speed; a feature many take for granted today.
Motivation for the Citation
To propel the Citation IV, Chevrolet decided to use a 2.8-liter, V6 engine with iron block and cast aluminum heads.
Fitted with a complete engine cooling system, air conditioning and full emissions control equipment, it delivered 140-horsepower which was up from the Citation II V6’s 112 horsepower. Power was fed to the front wheels through a three-speed automatic transmission with lock-up torque converter.
In general terms, the motor was unchanged but some of the details needed adjustment.
The Citation IV adopted most of the Aero 2002’s design characteristics, including the wedge-shaped front end. In order to meet lofty aerodynamic goals, the hoodline continues at the same angle as the windshield. If you’re curious what that angle is, from bumper-tip to windshield-top, it slopes at 68-degrees and the hoodline measures a full five inches lower than the hoodline of the production Citation II’s. It’s that dramatic lowering of the hoodline that posed an obstacle for drivetrain packaging.
With fuel injection only beginning to proliferate through the automotive world, much of a motor’s vertical clearance at the time was needed for the carbureted, as indicated in the diagram. To work around that, Chevrolet logically went with (electronic port) fuel injection. Even so, there was still not enough room to feed air to the motor in a conventional fashion.
To solve that problem, without altering the exterior design, both valve covers and the intake manifold were made from a one-piece aluminum casting which fed tuned passages to each cylinder. Air was sourced from a unique “snorkel” mounted in front of the left wheel well then channeled through an in-line filter. By replacing the top-mounted carburetor, air filter and separate intake manifold, roughly five inches of vertical clearance were saved. As a result of the intake design, torque and horsepower were reported to be on par with a high-output carbureted motor of the period.
Freeing up even more space underhood is the distributor-less ignition system that utilizes three high-tension coils, triggered by an electromagnetic sensor on the crankshaft.
Other space-saving measures include an oil sump that is two inches shorter than its contemporary counterpart, and a modified housing for the Turbo Hydra-matic transaxle that was rotated twelve degrees allowing the engine to be mounted two inches lower and a half-inch farther forward in the chassis.
A low, wide radiator was fed by the narrow, centered opening located below the bumper.
Interestingly, the three-slot opening that spans the front between the turn signals did not serve the engine bay but rather fed the passenger ventilation system. This was unique since cabin ventilation was typically pulled from the base of the windshield, a contoured area on Citation IV.
The flush mounted headlight lenses were highly effective but would not have been legal on US roads. There’s a reason domestic vehicles weren’t available with the so-called “European” lenses until the mid-1980s, but that’s a topic for a separate, forthcoming post.
Potential for Greatness
Despite serious efforts to reduce weight, the unibody Citation IV concept weighed in at about 2,600 pounds which was over sixty more than a production Citation II. Even so, thanks to the peppy engine, the Citation IV would scoot to 60 MPH in ten seconds flat and had a theoretical top speed of over 140 MPH.
While acceleration and top speed make for great talking points, the concept’s more practical goals had to do with efficiency. Chevrolet engineers anticipated the Citation IV would achieve 50 miles per gallon on the highway and, while traveling at 50 MPH, only require seven-horsepower of effort to push.
Drivability Conversion With Some Sacrifice
Citation IV was longer, lower and wider than Citation II. Specifically, it was 6.4 inches longer, 0.4 inch wider, 6.4 inches lower.
Despite the concept’s relatively enormous aerodynamic capability over the 1984 Citation II (which had a 0.432 Cd), it would be measured by many against the 0.14 Cd-achieving Aero 2002.
So, just how aerodynamic is Citation IV?
In full-blown, drivable guise (including outside mirrors, windshield wipers, etc.), the Citation IV achieves a 0.265 Cd.
That’s very respectable, although, nearly twice the drag than the Aero 2002 produced. However, Citation IV had a trick up its sleeve. It could be driven in a “modified” street trim which netted a 0.185 Cd. It made use of “inside peripheral mirrors,” hidden wipers, and a full, smooth underbody. Still drivable, but with some substantial modifications, it came very close to the record 0.14 Cd.
Despite losing some of its ability to slip through the air, it wasn’t all negative news. Citation IV not only had its own powertrain, but it also had a livable interior.
High Tech Habitation
The Citation IV has no exterior door handles or key openings. Entering requires use of the four-digit, heat-sensitive proximity buttons located high up on the pillar behind both doors.
Once access is granted, the doors open up wide enough to offer easy access to the rear seating. Soon-to-be occupants are greeted by an explosion of vibrant colors which was not uncommon for the early 1980s.
The bucket seats are made of “thin-mold urethane” which was required to maximize the interior space, however, oddly, the seats were not designed to recline.
The driver is faced with a digital read out. Incredibly simplistic by today’s standards but, in 1984, digital numbers and bar graphs were a glimps into the future, for many.
What was seemingly well ahead of its time was the heads-up display that showed the vehicle’s speed on the windshield in a manner similar to what fighter pilots were using. The “phantom-like digits” were described at the time by one popular automotive magazine as “conveying a velocity reading as if by magic.”
The rest of the interior was fairly standard issue with a Delco AM/FM radio and power equipment switchgear from GM’s parts bin. The Cavalier was harvested again, this time for some interior parts, such as the shift lever and steering wheel. The steering column-mounted switches were borrowed from the Camaro Berlinetta.
Although the rear quarters were said to be quite cramped on head room, the Citation IV’s shape paid off in reducing interior noise due to wind. Since most people at the time were accustomed to wind whistling around windows and doors, it’s no wonder those that drove it always remarked on its tomb-like quietness at highway speeds.
Mike Rosa - autosofinterest.com