Development of the Countach began in 1970 under the internal project name LP112, initiated by Ferruccio Lamborghini with the goal of replacing the acclaimed Miura. Chief engineer Paolo Stanzani led the engineering team, which included test driver Bob Wallace, assistant engineer Massimo Parenti, and designer Marcello Gandini of the Bertone studio. The design priorities were maximum performance, aerodynamic efficiency, and bold styling.
The name Countach originated from a Piedmontese exclamation of astonishment, coined informally during late-night working sessions by Gandini and his team. It broke with Lamborghini's tradition of bull-related model names. The LP designation stands for longitudinale posteriore, indicating the engine's longitudinal rear placement — shared across all Countach variants.
The first prototype, the LP500, was displayed at the 1971 Geneva Motor Show in bright yellow bodywork. It used a purpose-built 5.0-litre V12, but this engine destroyed itself during a 1971 road test conducted by Bob Wallace, demonstrating that further development was required. The LP500 prototype was subsequently fitted with a 3.9-litre engine for the remainder of pre-production testing, and was ultimately crash-tested at the MIRA facility in England on 21 March 1974 to gain European type approval.
A second prototype appeared at the 1973 Geneva Motor Show, featuring bodywork much closer to what would become the production LP400, including the side NACA ducts and air intake boxes tested on the first car. A third and final pre-production car was shown at the 1974 Geneva Motor Show in bright yellow and represented the finalised LP400 body style, which was 13 centimetres longer than the prototype bodies to increase interior space.
The Countach's styling was created by Marcello Gandini, who drew on his earlier concept work — particularly the 1968 Alfa Romeo Carabo and the 1970 Lancia Stratos Zero — to develop the wedge-shaped, aggressively geometric form. The scissor doors, which hinged upward and forward from horizontal pivots at the front of the door, were a direct carry-over from the Carabo and became one of the most recognisable design features in automotive history. Gas struts assisted opening and closing.
The LP500 prototype featured a crisp, uninterrupted wedge with retractable headlights, no bumpers, no aerodynamic spoilers, and trapezoidal shapes throughout its bodywork. Compared to the Miura it replaced, the prototype was wider and lower but shorter overall. During pre-production testing the nose slope was made shallower to reduce excessive front-end downforce that had destabilised the prototype under braking, and additional vents and NACA ducts were added to the doors and rear wings to address engine cooling.
The production LP400 measured 189 cm wide, 107 cm tall, and 414 cm long, slightly larger than the prototype. The futuristic all-digital dashboard and onboard diagnostic displays seen on the LP500 were replaced with conventional Stewart-Warner analog gauges for production. The prototype's periscope rear-view mirror, fitted instead of a conventional mirror to address the inherently poor rearward visibility, was retained on the LP400 but replaced with conventional mirrors on later variants.
The LP400 used Lamborghini's 3,929 cc (3.9-litre) V12 engine, originally designed by Giotto Bizzarrini in 1963 and previously employed in the Miura. As fitted to the LP400, it was rated at 276 kW (375 PS; 370 hp) at 8,000 rpm with 266 lb-ft of torque at 5,500 rpm. The engine designation was L 406. Unlike the Miura's transversely mounted engine, the Countach used a longitudinal layout — the first road-going V12 to do so, a configuration previously used only in Ferrari's P-series racing cars. To improve weight distribution, the transmission was placed in the middle of the car between the two seats, with the driveshaft running through the engine's oil sump to a rear differential. This arrangement produced a shorter wheelbase, more direct gear-shift feel, and better mass centralisation than the Miura achieved.
The LP400 rode on Michelin XWX tyres sized 205/70R14 at the front and 215/70R14 at the rear. The narrow tyres and uncluttered bodywork gave the LP400 the lowest drag coefficient of any Countach production model.
The chassis was a full tubular space frame of welded round-section steel tubing, fabricated by Marchesi of Modena before being delivered to Lamborghini's factory at Sant'Agata Bolognese for assembly. This technique was used in Formula One at the time but was exceptionally advanced for a road-going automobile. The body panels were hand-formed aluminium fabricated by Bertone. Each V12 engine was run for five hours and inspected before installation in the car.
The LP400 was first offered for sale at the 1974 Geneva Auto Show, where fifty orders were placed at the event. Production continued until 1978, by which point 157 LP400s had been built. At the rear, the emblems read simply "Lamborghini" and "Countach" without engine displacement or valve markings, a practice unique to the LP400 among Countach variants.
Between 1974 and 1976, a small number of LP400s were assembled in Cape Town, South Africa, by local dealer Intermotormakers, which imported the cars as complete knock-down kits. The total number assembled by Intermotormakers is unknown but constitutes a very small fraction of overall production. The arrangement ended after the South African government revoked Intermotormakers' exemption from a local-content manufacturing requirement in 1980.
In 1978 the LP400 was succeeded by the LP400 S, which introduced wider Pirelli P7 tyres sized 345/35R15 — the widest available on any production car at the time — along with fiberglass wheel arch extensions that gave the Countach its more muscular later appearance. The LP400 S engine was marginally downgraded to 350 PS at 7,500 rpm. Three series of LP400 S were produced, totalling 237 cars. The LP500 S followed in 1982 with a 4,754 cc engine and 321 examples built, succeeded in 1985 by the LP5000 Quattrovalvole with a 5,167 cc four-valve-per-cylinder engine. A 25th Anniversary Edition appeared in 1988, featuring substantial restyling by Horacio Pagani, before production ended in 1990 with the introduction of the Diablo. Across all variants, 1,983 Countachs were produced.
The LP400 is regarded by many collectors and historians as the definitive Countach — the version that most faithfully realises Gandini's original design intent before the successive additions of wider arches, spoilers, and carburetor covers altered the silhouette. Between 1980 and 1983 the Countach served as the Formula One safety car at the Monaco Grand Prix. Its scissor doors were adopted by subsequent Lamborghini models and its poster-car status shaped popular perceptions of the supercar category throughout the 1970s and 1980s.