Lancia did extensive testing with the Stratos and raced the car in several racing events where Group 5 prototypes were allowed during the 1972 and 1973 seasons. Production of the 500 cars required for homologation in Group 4 commenced in 1973 and the Stratos was homologated in time for the 1974 WRC. The Ferrari Dino V6 engine was phased out in 1974, but 500 engines were delivered to Lancia. Production ended in 1975, at which time only 492 were possibly completed (for 1976 season, the Group 4 production requirement was reduced to 400 in 24 months). The responsible manufacturer of the car was Bertone, in Turin, with final assembly completed by Lancia at the Chivasso plant.
Powered by the Dino 2.4 L V6 engine that was also fitted to the rallying versions, but in a lower state of tune, it resulted in a power output of 190 bhp (142 kW; 193 PS), giving the road car a 0-60 mph time of just under five seconds, and a top speed of 144 mph (232 km/h). The car was sold as the Lancia Stratos Stradale.
For racing, the engine was tuned up to 280 hp (209 kW) and even to 560 hp (418 kW) with a single KKK turbocharger. However, turbocharged versions were only allowed to compete in Group 5 and were never as reliable as their naturally aspirated counterparts.
The car won the WRC titles in 1974-76 in the hands of Sandro Munari and Björn Waldegård, and might have gone on to win more had not internal politics within the Fiat group placed rallying responsibility on the Fiat 131 Abarths.
Without support from Fiat, and despite new regulations that restricted engine power, the car would remain a serious competitor and proved able to beat works cars in several occasions when entered by an experienced private team with a talented driver. The final chapter of the Stratos’ racing career at international level took place as late as 1981, at the Tour de Corse Automobile, another World Rally Championship event, with a victory by longtime Stratos privateer Bernard Darniche.