Never use fabric softener on any towels, cotton or microfiber

your bath towels lose absorbency with fabric softener (works as water repellent), residue causes a problem with drying your car (got streaks?)

Softener is a big no-no - I have microfibers and can dry on low in dryer with no ill effects, use the microfiber cleaner from Griot's Garage - stuff is great for foam pads and microfibers in the washer with mild detergent and no softener (did I mention no softener?)