I bought an automated car wash. Here's how my husband and I turned a $16,000 investment into 3 locations that made $340,000 in profit last year.

• BreAnna Nixon and her husband put down a $16,000 payment on a self-service car wash in 2017. 
• They only wanted a second income when they began the venture with Nixon's brother and his wife. 
• But they went full-time after two years and made $340,000 last year, working 20-hour weeks.

This as-told-to essay is based on a conversation with BreAnna Nixon, who bought a car wash as a side hustle that is now her full-time business. The following has been edited for length and clarity.