Based on the rear wheel drive GM X-body platform that underpinned the Chevrolet Nova. The Seville's unit body and chassis were extensively re-engineered and upgraded from that humble origin and it was awarded the unique designation of "K-body". Cadillac stylists added a crisp, angular body that set the tone for GM styling for the next decade, along with a wide-track stance that gave the car a substantial, premium appearance.
   Seville engineers chose the X-body platform instead of the German Opel Diplomat in response to GM's budget restrictions - GM executives felt that rebadging a German Opel would be more costly than the corporate X-car. Another proposal during the development of the Seville was a front-wheel drive layout similar to the Cadillac Eldorado. This proposal also met with budget concerns since the transaxle used for the Eldorado was produced on a limited basis solely for E-body (Eldorado/Toronado) production.
   This was the first time Cadillac based one of its vehicles on a Chevrolet model. This trend continued with the Cimarron in 1982 and is repeated more recently with the Escalade and XLR.
   Introduced in the mid-'75 and billed as the new "Internationally-sized" Cadillac, the Seville was almost 1,000 lb (450 kg) lighter than the hulking DeVilles, nimble, easy to park, attractive and loaded with the full compliment of Cadillac gadgets. More expensive than every other Cadillac model at $12,479, the Seville was a smash hit, and spawned several imitators, such as the less-than-successful Lincoln Versailles, and later the Chrysler LeBaron/Fifth Avenue.
   The first Sevilles produced between April 1975 (a total of 16,355) to the close of the 1976 model year were the only Cadillacs to use the Chevrolet passenger car wheel bolt pattern (5 lugs with a 4.75 in bolt circle). At first, the Sevilles were essentially a rebodied Chevrolet Nova down to the brakes. The rear drums measured 11 in and were similar to the ones used with the Chevrolet Nova 9C1 (police option) and A-body (Chevelle, Cutlass, Regal, LeMans) intermediate station wagons. Starting with the 1977 model year, production Sevilles used the larger 5 lug - 5 inch bolt circle common to full-size Cadillacs, Buicks, Oldsmobiles, Pontiacs, and 1/2 ton Chevrolet/GMC light trucks and vans. It also received rear disc brakes, a design which would surface a year later as an option on the F-body Pontiac Trans Am.
   Under the hood went an Oldsmobile sourced 350 in³ (5.7L) V8, fitted with Bendix/Bosch electronically controlled fuel injection. This system gave the Seville a smooth drivabilty and performance sadly lacking in most other cars of the mid-seventies. Power output was 180 hp, and performance was restrained with the 60 mph sprint taking 11.5 seconds. A Diesel 350 in³(5.7 L) LF9 V8 was added in 1978, but that engine was known to be poor in both performance and reliability.