Accepting credit cards at the car wash is a hot topic among car wash owners, but I recommend looking into having them seriously. Surveys have consistently shown that people who pay with plastic (credit or debit) tend to spend more per purchase than those who pay with cash. At most car washes, credit card customers generally spend 20-30% more than cash customers, which makes the CC fees easier to recoup. Generally speaking, anything you can do to make it easier for motorists to buy your services is usually a good decision. Adding credit card machines will cost roughly $1000 per car wash bay plus monthly and transaction fees.