The present invention relates to a method for applying a detergent use solution to a washing surface of a motor vehicle, including the steps of: (a) providing a liquid detergent concentrate that includes an active ingredient level from about 0.1 wt.% to about 15 wt.%; (b) introducing the liquid detergent concentrate into a water stream to provide a detergent use solution that includes an active ingredient level from about 0.03 wt.% and 1 wt.%; and (c) applying the detergent use solution to a washing surface of a motor vehicle. In addition, the present invention also relates to a method for washing a washing surface of a vehicle, wherein the method includes: (a) providing a liquid detergent concentrate having an active ingredients level from about 0.1 wt.% to about 15 wt.%; (b) introducing the liquid detergent concentrate into a diluent stream to provide a detergent use solution; and (c) applying the detergent use solution to a washing surface of a vehicle wherein the detergent use solution has a relatively constant active ingredients level over the entire washing surface during a wash cycle.