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This or That – Season 3: 1975 Plymouth Road Runner or 1976 Buick Century Pace Car Replica?

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1975 Plymouth Road Runner (top, image by Terry McGean); 1976 Buick Century Indy Pace Car Replica (bottom, image by the author).

Editor’s comment: Please note that the This or That column is not a comparison report between two vehicles, but rather a feature that enables us, in an idyllic world, to add a collectible vehicle into our dream garage on a regular basis, but with a catch: We can only pick one vehicle from this pairing, and it has to be for enjoyment purposes rather than as an investment. So let’s climb into the ultimate automotive fantasy time machine and have a little fun.

Featured in this edition of This or That are a pair of intermediates: a 1975 Plymouth Road Runner and a 1976 Buick Century Indy Pace Car Replica. Both had proud performance pasts. The former of the two was famously released on the streets of 1968, a reinvented interpretation of the muscle car breed as the supercar era edged closer to its as-yet unseen peak. Budget-friendly Speedious Maximus was claiming street-n-strip wins within days. Buick’s Century is arguably the earliest example of the muscle car mold, created when the division’s engineers dumped the high-output Roadmaster/Limited engine in a newly minted midsize chassis in 1936; the name “Century” directly related to Buick’s claim of a 100-mph top speed as a result. After a brief hiatus, Century was winning stock car races by the mid-Fifties. As we’re all too aware, however, government and insurance regulations — coupled with the baby boomer’s very real (and often overlooked) swing in automotive needs — had crippled hi-po hijinks by the mid-Seventies, leaving these nameplates all dressed up with nowhere to go. In theory. Before passing judgement, here are a few details about each car (if you want to read more than we’ve provided, both vehicles were former subject material in our Hemmings Muscle Machines magazine — just click on the links above).

Period literature boldly claimed that the 1975 Road Runner, “…makes you forget that mistaken notion that cars can’t be fun anymore.” Having landed on the unit-body Fury-based B-body platform, Mother Mopar attempted to make good on that claim by offering a two-barrel, 150-horse 318 as standard equipment (insert yawn here), which could have been supplanted by one of five — count ’em — options. First up was the two-barrel 360 rated for 180 hp, followed by a 190-horse version made possible by a four-barrel carburetor. Then there was the 165- and 190-hp versions of the two- and four-barrel, respectively, topped 400, which was accompanied later in the model year by the heavy-duty 400: a four-barrel, dual exhaust big-block that thumped out 235 hp. [Editor’s note: California emission laws either outlawed or stipulated changes that affected output ratings — refer to the original article for more details.] Only one manual transmission was offered, a three-speed against the 318, meaning an overwhelming number of Road Runners left the assembly line with the TorqueFlite automatic. Despite this, a hint of seat-of-the-pants performance was provided by the optional 9.25-inch differential with the Sure Grip system.

Beyond the mechanical composition, visual cues and cabin comfort were somewhat unique. According to the original article…

To say that the new Road Runner took its styling cues from the redesigned two-door Fury is an understatement. It shared every body panel, right down to the single headlamp bezels, with its sibling. Yet Plymouth made a point of separating the once-proud performer from the Fury fleet — not a single Fury badge could be found anywhere on the Road Runner. Furthermore, only the Road Runner came with a blacked-out grille (sparsely trimmed with chrome); “up-and-over tape stripes keyed for use with a total of 18 [exterior] colors”; the famed “Road Runner” script on each door, accompanied by the running bird decal; and stationary bird emblems within the grille and in decal form on the rear decklid. Another, more elaborate trunk decal was a Road Runner exclusive option, which featured a tunnel-effect graphic, often referred to today by enthusiasts as the “Star Wars” decal. Also on the option sheet was a manually operated sunroof and a choice of Canopy or Halo-style vinyl roof coverings in six colors.

Interiors were personal-luxury plush: bucket seats or optional bench, finished in pleated vinyl in a handful of colors, or — as seen in our feature car — the colorful cloth/vinyl Sundance scheme with matching door panels. Thick carpet was underfoot, while the cabin was surrounded by ample sound-deadening material within the body panels. One of the few areas where the ’75 Road Runner seemed more sporting than the original was the instrument panel, which featured a circular speedometer with a matching circular binnacle to the right that could be filled with an optional electric clock or, better still, a tachometer. An optional Tuff steering wheel provided a direct link to more muscular times; a choice of five radios and other power accessories was also on the option chart.

Obligatory chassis upgrades (a few heavy-duty components) also made the cut for the one-year-only B-body Road Runner, which only managed to attract 7,183 customers. To give one a sense of how far things had come, contemporary road tests of the model (fitted with a 190-hp 400) produced a 17.1-second quarter-mile time.

Buick, meanwhile, had been busy laying the groundwork for a new performance solution that pacified government economy and emission regulations, and it just happened to coincide with the division’s selection to pace the Indianapolis 500 in both 1975 and ’76, particularly the latter of the two. As stated in the original article,

The 1976 Buick Century pace car was significant for being the first V-6 powered version to lead the pack, but it also sparked a long relationship between the Buick V-6 and turbocharging. The replica pace car looked the part, but did not pack the 300-plus horsepower punch of the V-6 pace car — even with a Buick V-8.

The requirements for a pace car were different than those for street cars. Being able to sustain 120 mph without flying was one of them. Anyone who has ever taken a muscle car into the triple digits knows that floating can be an issue when maintaining speeds approaching 120 mph. According to a Buick engineer quoted by Mike Knepper in the June 1976 Motor Trend, the key requirements for an Indy pace car were simple but critical: Turn three exit of 90 mph. Turn four at 110 mph. Peeling off the track into the pit lane was a 120-mph affair. Even with only 231 cubic inches, the turbo V-6 provided a faster and more consistent sprint from 90-110, and the crucial 120 mph for the exit, than the 455 cubic inches of V-8 used the year prior. A front air dam and rear spoiler helped fight against flight.

…the Buick turbo V-6 was destined for greatness, and while its street and strip glory was still a few years in the future with the Regal Grand National, a production V-6 turbo would first appear shortly after the ’76 pace car with the launch of the 1978 Regal lineup. Those early 3.8-liter turbo sixes — offered with either two- or four-barrel carburetors — weren’t all that impressive, but as the Eighties unfolded, electronic fuel injection and intercooling would conspire to yield the true greatness of the Buick V-6 turbo.

As alluded to, since a production version of the turbocharged V-6 was two years into the future, the official Century pace car replicas were instead fitted with the 165-hp version of the division’s own V-8, backed by a TH350 automatic transmission. Indy graphics aside, other standard features included Hurst Hatch T-tops, brushed aluminum roof trim, color-keyed road wheels, and sport mirrors. Buick issued just 1,290 Indy pace car replicas for 1976, and according to time slips provided to us at the time its feature was penned, the stock Century produced a quarter-mile time of 18.864 seconds @ 74.01 mph.

To reiterate, this was the “more flash, less gas” era, when “personal luxury” reigned as sales supremo. Keeping everything in proper context, which of the two would you add to your dream garage and why?