It emerged last month that Rauf had sworn allegiance to IS after falling out with the Taliban.
Tribal elders in northern Helmand say a car carrying up to six people was destroyed while crossing the desert.
The car was loaded with ammunition and exploded, reports said.
The commander killed in Helmand, Mullah Abdul Rauf, was appointed deputy commander in the region.
The air strike that killed him was one of the first reported under Nato’s new mandate.
