Equipped with a equation for WRC domination, a high-power + 4WD system, the Delta S4 was powered by a mid-mounted 1759cc inline-four engine. The engine was equipped with Abarth supercharger to ensure torque in the low-rotation range and a KKK turbocharger to obtain power in the high-rotation range. It was said that the power, which was said to be 450 hp, reached 550 horsepower at the end of 1986. The chassis with mid-mounted engine adopt a steel tubular space frame construction. The mid-mounted engine in the back and forth direction, and the power was distributed back and forth from the gear box placed in front of the engine. the chassis adopts a steel pipe space frame structure. The engine and the gear box were mounted in the opposite direction and forward and backward, and the power was distributed back and forth from the gear box placed in front of the engine. The body left the image of consumer family car, the Delta 5-door hatchback, but the design was entirely different.

The Jolly Club team, known as Italy’s prestigious privateer, ran the DELTA S4 in TOTIP livery. Besides WRC, DELTA S4 also ran for the European Rally Championship and the Italian Rally Championship. At the Sanremo Rally in 1986, Dario Cerrato won second place following Works’ Miki Biasion.