The Lancia Delta S4 is a Group B rally car that competed in the world rally championship in 1985 and 1986 after which the Group B was banned due to too many fatalities.

The S4 had a inline 4-cylinder 1.8 liter engine with a turbocharger and a supercharger. This little engine developed around 490 horsepower although in testing it was pushed all the way to 1000 horsepower. It was equipped with all-wheel drive developed with Hewland. Unfortunately the car was severely lacking in safety features and the accident where Lancia driver Henri Toivonen perished caused FIA to disband Group B rallying.