Abstract: Helical compression spring for use in an actuator for opening and closing a door or a tailgate of a car has an outer diameter between 15 and 50 mm and comprises a helically coiled steel wire. The steel wire has a non-circular cross-section with an equivalent diameter d (in mm) of the steel wire is between 1 mm and 12 mm. The cross-section may have at least two opposing parallel sides. The cross-section further has rounded edges, wherein the rounded edges have a radius of curvature ranging from 0.10 mm to 5.0 mm. The microstructure of the steel wire in the helical compression spring is cold deformed pearlite. In comparison with helical compression springs with round cross-sections, the non-round helical compression springs may occupy less space or reach higher breaking loads within the same space.