When assessing performance, prioritize machines with high-pressure water systems (100-150 bar) and intelligent vehicle contour recognition using ultrasonic or infrared sensors. Ensure the frame is made of hot-dip galvanized steel or 304 stainless steel to prevent corrosion from constant water and chemical exposure. For touchless models, check the nozzle rotation speed and coverage, while for brush models, verify the use of EVA or foam brushes which are gentler on vehicle paint than traditional nylon.