Why is pre-washing a very important phase on a car wash system?

Pre-washing is fundamental not only for particularly dirty vehicles but also for routine cleaning. It always ensures excellent results, in full compliance with paint and brushes.
Actually, residues may pile up on brushes and, over time, decrease their efficiency shortening the product life cycle and affecting their smoothness.
That is why really good pre-washing is always highly recommended both for the benefit of the car wash supervisor and for customers.