The ECV (Experimental Composite Vehicle) would have had to take the place of the Delta S4 had the regulations not been changed at the end of 1986, abolishing Group B in favor of Group A, for which Lancia developed the Delta HF 4WD. The ECV had an 1800cc 4-cylinder engine no longer equipped with a compressor, like that of the S4, but with an innovative twin-turbo system, called Triflux, designed by engineer Claudio Lombardi. The power of the ECV reached 600 horsepower at 8000 rpm.