Development began around 1970, when Ferruccio Lamborghini commissioned chief engineer Paolo Stanzani to design a Miura successor capable of beating new rivals such as the Ferrari Daytona. The project was initially called LP112. Stanzani worked alongside Gandini, assistant engineer Massimo Parenti, and test driver Bob Wallace to combine maximum performance with aerodynamic efficiency and aesthetic boldness.
The name "Countach" came from a Piedmontese dialect exclamation of astonishment — contacc — used habitually by a tall craftsman working night shifts in Bertone's workshop. Gandini applied it to the car as a joke, found it worked to an Anglo-Saxon ear when pronounced by Bob Wallace, and the name stuck. The naming system that followed used "LP" (from longitudinale posteriore, meaning the engine is mounted longitudinally at the rear) followed by a number indicating nominal displacement: LP400 for the 3.9-litre cars, LP500 for larger-displacement variants.
The prototype, called the LP500, debuted at the 1971 Geneva Motor Show in bright yellow bodywork. Its wedge shape, scissor doors, periscope rear-view mirror, aircraft-style warning lights, and on-board diagnostic display attracted enormous attention. The scissor doors, which hinge at the front pillar and swing upward and forward, were first seen on Gandini's 1968 Alfa Romeo Carabo concept. They were chosen partly for styling and partly because the car's wide chassis and high door sills made conventional outward-swinging doors impractical in tight spaces.
The Countach used a Lamborghini V12 engine derived from a 1963 design by Giotto Bizzarrini. Stanzani mounted it longitudinally — a first for a road-going V12 — and placed the five-speed manual transmission ahead of and between the two seats, connected to the engine's front output shaft via the clutch. The driveshaft then ran rearward through the engine's oil sump to a differential at the tail. This configuration placed heavy components near the car's centre, shortened the wheelbase, and gave faster, more direct gearshift action than the Miura's transverse layout permitted. The space frame chassis, fabricated from hand-welded round-section steel tubing, was advanced enough that the same construction method was being used contemporaneously in Formula One.
The LP500 prototype's experimental 5.0-litre V12 destroyed itself during a 1971 road test. The production LP400, launched at the 1974 Geneva Auto Show, therefore used the proven 3.9-litre unit rated at 276 kW (375 PS; 370 hp) at 8,000 rpm. Body panels were formed from aluminium, hand-shaped during final assembly. A total of 157 LP400s were built by 1978.
The LP400 S, introduced in 1978, fitted the widest production-car tyres then available — 345/35R15 Pirelli P7 items at the rear — requiring wide fibreglass arch extensions that defined the car's visual identity for the remainder of its run. Engine power was marginally reduced to 350 PS. An optional V-shaped rear wing, popularized by a special car built for Canadian businessman Walter Wolf, was chosen by most buyers despite reducing top speed by at least 16 km/h. Three distinct LP400 S series were produced totalling 237 cars.
The 1982 LP500 S raised displacement to 4,754 cc and power to 276 kW at 7,000 rpm; 321 examples were built.
The 1985 LP5000 Quattrovalvole (5000 QV) grew the engine to 5,167 cc and added four valves per cylinder. Weber carburetors moved from the engine sides to the top, creating a hump on the engine cover that further reduced already limited rearward visibility. European carbureted versions produced 335 kW (455 PS; 449 hp); US-market cars used Bosch K-Jetronic fuel injection and were rated at 313 kW. Some body panels were replaced with Kevlar. The 5000 QV was the best-selling variant, with 610 cars built.
The final production model was the 25th Anniversary Edition of 1988, restyled extensively by Horacio Pagani. The rear air intake ducts were enlarged and repositioned for improved cooling airflow, and the engine cover was redesigned. The Anniversary Edition accelerated from 0 to 97 km/h in 4.7 seconds and achieved a top speed of 295 km/h (183 mph), making it the fastest and most refined Countach of the series. Production continued until 1990, when the model was superseded by the Lamborghini Diablo.
The United States was Lamborghini's largest market, but neither the Countach nor the Ferrari Berlinetta Boxer was built to meet US safety and emissions regulations. American buyers purchased cars through a grey market that required individual modification to comply with Environmental Protection Agency and Department of Transportation rules. The grey market in exotic and other non-compliant vehicles grew to 66,900 vehicles in 1985 before regulatory changes curtailed it. From 1985, Lamborghini produced a factory US-specification 5000 QV with larger energy-absorbing bumpers and fuel injection to meet federal standards. Many buyers removed the enlarged bumpers immediately after purchase.
The Countach's basic proportions — established at the 1971 Geneva show and carried through virtually unchanged — remained in production for 19 years across five distinct variants. Its scissor doors became a defining Lamborghini signature retained on subsequent models including the Diablo and Murcielago. The space frame chassis and extensive use of aluminium bodywork anticipated manufacturing approaches later applied more widely in low-volume supercar construction.