By the mid-1960s Ferrari had dominated sports prototype racing with the P-series of 4-litre V12 cars, but a rules change for 1968 restricted Group 6 prototypes to 3.0-litre engines, and Ferrari sat out that season before returning in 1969 with the Ferrari 312 P. In late 1968, Porsche made the bold investment of developing and building 25 examples of the 4.5-litre Porsche 917, exploiting the FIA's Group 4 homologation category for 1969. The sportscar world was surprised by the 917's potential. Already selling half his business to Fiat, Enzo Ferrari diverted funds to mount a direct response.
The 512 S engine was a completely new 60-degree V12 architecture, contrasting sharply with Porsche's air-cooled flat-12. It required an extensive cooling system with a heavy radiator, and the steel chassis reinforced with aluminium sheet weighed approximately 100 kg more than the alloy-framed 917. Despite this weight and a higher centre of gravity, the two cars were considered fairly evenly matched in outright pace.
Twenty-five cars were presented to homologation authorities in January 1970, as 17 complete cars and eight assembly kits, using traditional Ferrari even-numbered chassis numbers ranging from 1002 to 1050. Nineteen were raced during 1970, including five spyder variants.
Ferrari entered the 512 S under the "Spa Ferrari SEFAC" banner in the traditional works manner rather than adopting Porsche's strategy of supplying multiple professional satellite teams — JWA Gulf, Porsche Salzburg, and later Martini Racing — with direct factory support. This structural disadvantage meant Ferrari's works cars competed without the same consistent technical and logistical backing that Porsche's supported teams enjoyed.
The season began promisingly when Ferrari won the 1970 12 Hours of Sebring (chassis 1026). However, the Porsche 917, backed by teams with stable driver pairings and comprehensive support, took the remaining nine championship race victories. The 512 S's greatest difficulty came at the 1970 24 Hours of Le Mans, where four factory cars were entered and all retired: the Vaccarella/Giunti car failed after seven laps, Merzario/Regazzoni after 38, Bell/Peterson a lap later, and the Ickx/Schetty car after 142 laps.
Ferrari's factory driver roster across 1970 totalled twelve different pairings, with Ignazio Giunti appearing in nine of the ten championship rounds. Other regular drivers included Jacky Ickx, Clay Regazzoni, Nino Vaccarella, Peter Schetty, Arturo Merzario, Mario Andretti (American rounds only), Derek Bell, and John Surtees. The driver situation was complicated by Ferrari's simultaneous Formula One programme: Ickx finished second in the 1970 F1 World Championship and Regazzoni third, leaving neither fully available for the endurance effort.
Late in 1970, a modified version of the car was introduced, designated the 512 M (for modificata), featuring aerodynamic bodywork redesigned to more closely resemble the long-tail Porsche 917. This variant proved quicker than the standard S, and Ickx and Ignazio Giunti won the non-championship Kyalami 9 Hours in a 512 M at the end of 1970. Ferrari abandoned factory 512 entries for 1971, focusing development resources on the new 3-litre Ferrari 312 PB, but privateer teams continued to campaign the 512 M. The Penske team entered an improved 512 M (chassis 1040) in Sunoco livery during 1971 and was capable of challenging the 917, taking pole positions at several American venues.
The 512 S appeared at the same circuits and in the same era as some of the most celebrated sports cars ever built, yet was ultimately outclassed by the more comprehensively supported Porsche campaign. The sole major 512 S championship victories were at Sebring (chassis 1026) and the non-championship Kyalami race (chassis 1010 in 512 M specification). Several chassis had notable post-racing histories: chassis 1036 was sold to Solar Productions for use in Steve McQueen's racing film Le Mans, before being converted to an open-top version for Can-Am racing in 1974. One 512 chassis and its V12 engine were also provided to Pininfarina for the creation of the Ferrari Modulo concept car.
Three of the twelve factory drivers who raced the 512 S in 1970 did not survive the decade: Ignazio Giunti was killed at the 1971 Buenos Aires 1000 km, Ronnie Peterson died from injuries sustained at the 1978 Italian Grand Prix, and Clay Regazzoni, paralysed in an accident at the 1980 United States Grand Prix West, died in a road accident in Italy in December 2006.