Let’s pretend that you are the massive corporate fiefdom that was General Motors in the 1970’s. Hitherto you could do largely as you wished, but then something called CAFE happened, and it didn’t involve a blue plate special. Corporate Average Fuel Economy is what I mean, a choice piece of legislation enacted in 1975 in response to the oil embargo of 1973-74. Suddenly what was good for the nation wasn’t necessarily good for GM. In short order the behemoth corporation had to revamp its product line and reach a corporate average fuel economy of 18 mpg by 1978. And this was in the days when anything less than 400 cubic inches was kinda, well, small and your average B body (GM speak for the full size platform) tipped the scales in the neighborhood of two and a quarter tons. Clutch in the AC compressor on a big block powered car and single digit consumption was an ugly reality as petrol poured like Niagara Falls from the carburetor jets. This was, to say the least, highly undesirable when gasoline was starting to be as hard to come by as a virgin in a bordello.
Presumably because the most gain could be derived from shrinking the largest and therefore, thirstiest cars the General chopped the B bodies first. As was the vogue, designers took a hard look at Mercedes, for at that time Mercedes was selling a lot of sensible, well screwed together cars. Vee don’t like zings vich are not evvishent ! The General wasn’t too interested in screwing them together as tight as Mercedes, but they were willing to take a few pointers on packaging. A 1976 Bonneville had a wheelbase of 123.4 inches, a 1977 Bonneville had a 115.9 inch wheelbase and a 1976 Mercedes 450SEL had 116.7 inches between the axles. The overall length of a ’76 Bonnie was 226 inches even, post downsize they measured up at 213.8 inches, just 4.4 inches longer than a 1976 450SEL. The liposuction removed the better part of half a ton from the car’s curb weight, but apparently only from the outside. Interior dimensions remained comparable to the old B bodies, and in some cases were improved, notably trunk capacity and rear seat legroom were both up. European space efficiency may have influenced packaging, but old ideas die hard and the 1977 B bodies still had a separate ladder frame. Presumably, this was for NVH attenuation. The frames were a lighter weight, it was said you could kick one and watch it quiver.The bodies were something of a 3/4 monocoque, the two had to be bolted together to realize a structurally sound whole. Suspension followed conventional practice with a live rear axle and control arm front suspension. Steering was still recirculating ball (just like Mercedes !).
There’s no replacement for displacement, unless you add lightness. Engine sizes were down too, and six cylinders were again available in the big cars. Sixes were in a straight line at Chevy, BOP got a bent six from Buick. Really big displacement engines were all jettisoned, except over at Cadillac, where for the moment, one could still get a 425 inch version of that division’s V8, though this had been emasculated considerably from its glorious 500 cubic inch swept volume. In the name of economy, some GM cars of the era came with a “fuel economy gauge”, a sort of interactive feedback to encourage the driver to be as ginger as possible on the right pedal. This was, in reality an intake manifold vacuum gauge, but was an interesting idea which no doubt appealed to the fathers (and grandfathers) of today’s hybrid car fuel economy zealots.
General Motor’s various divisions were still semi independent principalities in those days, but the new trim B bodies were the result of the combined efforts of all the divisions. Chevrolet designed the frame and front suspension, Oldsmobile was in charge of steering and fuel systems, Pontiac developed the bumper systems and so on. Corporate level committees oversaw the work of each division to make sure that tab A would intersect with slot B when the time came to start cranking them out. The net result was the most homogeneous big car from the General ever. It also resulted in a division’s flagship car that was about the same size as the existing intermediates, yet cost more. This created a bit of a conundrum for dealers who had to shift units.
Viewed from today’s perspective, we tend to think of these cars as land yachts, but they weren’t really.They had a trim tailored shape that I speculate was heavily influenced by Cadillac’s “international sized” Seville and nice slender pillars for visibility (I’d like to see the return of such pillars, if you could see out of sedans maybe people would stop buying tall SUVs). By way of comparison, a 1977 six cylinder Caprice weighed in at around 3700 lbs, a 2016 Impala approximately 3600-3800 lbs and a 2016 Accord is in the region of 3170-3600 pounds. On a by the pound basis, a 2016 sedan is directly comparable to a 1977 B body. Of course, engine technology has come along way and today you can actually have enough power in your just-sub-two-ton-sedan to move with serious alacrity. Never mind that you need to use both hands to count the gear ratios in an automatic transmission ! The shrunken, rationalized B bodies of 1977 don’t represent the last gasp of neolithic body on frame construction and pushrods, they represent the first steps in the way forward to rationalized products and economical operation. They were very successful cars both in terms of numbers sold and the yeoman service they gave individuals, taxi companies, law enforcement and no doubt others that I can’t even think of. Indeed, in my misguided youth I briefly possessed and ruthlessly abused a white 1979 Caprice Classic coupe with tan vinyl guts, aero back glass and a carbureted 350. Wish I had it still.