Upper-middle-class luxury remained Oldsmobile's mainstay in the '70s, and its big cars never strayed from it. What they did stray from, eventually, was needless bulk, which had become an increasing liability in the more-energy-conscious climate of late decade.
GM bowed the largest full-size cars in its history for 1971, so Oldsmobile's B-body Delta 88 and C-body Ninety-Eight acquired extra inches and pounds on wheelbases unchanged from '69. Big-block 455 V-8s prevailed, but were progressively detuned to meet ever-stricter emissions standards.
Wagons in this design generation had an interesting "clamshell" rear window/tailgate that retracted electrically into the body like a rolltop desk. The big Chevy, Pontiac, and Buick wagons all had it too, but it worked none too well.
As with Cutlass, the full-size Olds lost none of its appeal when downsized for 1977. If anything, these smaller big cars sold even better than the bigger old ones, doubtless due to improved fuel economy and maneuverability with no sacrifice in passenger room and ride comfort. Wheelbases contracted to 116 inches for Delta 88 and the Custom Cruiser wagon, and to 119 for Ninety-Eight, sizes that would persist through the mid-'80s.
Substantial weight reductions allowed the use of 350- and 403-cid V-8s without compromising performance. DieselV-8s and Buick's 231 gas V-6 were standard or optional from 1978 on. Model choices changed several times, but sedans and coupes usually ran to base, Royale, and Royale Brougham Deltas, and Luxury and Regency Ninety-Eights. The Custom Cruiser hung on in this form all the way through 1990, mainly because GM elected not to replace it with a smaller front-drive model that would have been less useful as a full-size wagon.
The personal-luxury Toronado evolved through the '70s more or less in step with the full-size Oldsmobiles. For 1971, it also became as large as it would ever be, going from mild sportiness to outsized opulence on a 123-inch wheelbase. Styling also changed -- mostly for the worse -- becoming more contrived and Cadillac-like through the end of this second generation in 1978.
Two Toronado styling developments in these years bear mention. One was a throwback to the early-postwar Studebaker Starlight coupes: a huge rear window wrapped around to the sides in a near unbroken sweep on the XS model of 1977 and XSC of 1978. More laudable was a second set of brake lights just below the rear window, the precursor to an idea that would later be mandated by Washington for all cars sold in the U.S.
Despite its innovative engineering, the Toronado had no direct technical bearing on GM's linewide switch to front drive that began with the 1980 X-body compacts. In fact, it would probably have sold just as well with rear drive -- as indeed did Buick's Riviera, which used a rear-drive version of the Toronado platform after 1965 but was always more popular.
Save 1973, when sales neared 56,000, second-series Toronado volume was hardly exceptional: about 23,000 in most years. The new downsized generation of 1979 was smaller than even the 1966 original, with a 114-inch-wheelbase E-body platform and adequately potent small-block V-8s. It immediately garnered a bit more than 50,000 orders, then pulled in from 34,000 to 48,000 a year through 1985.