The Best Car Wash Brush (Review) in 2021 | Car Bibles Ettore Extend-A-Flo Auto Wash Brush. Best Budget Flow-Through. slide 1 of 1. CHECK LATEST PRICE. Another option that features a flow-through pole is the Extend-A-Flo from Ettore. Amazon customers rate the brush very highly thanks to its ergonomic grip and integrated shut-off valve for greater water flow control.