2016 BMW Z4 Submodel: sDrive28i; Engine: 2.0L L4; Location: Reservoir;. 2016 BMW Z4 Submodel: sDrive35i; Engine: 3.0L L6; Location: Reservoir;. Part Type: Engine Coolant Reservoir Cap. 2016 BMW Z4 Submodel: sDrive35is; Engine: 3.0L L6; Location: Reservoir;.