Zack (Blue-Collar Billionaires #4)
M. Malone

As the daughter of a congressman, Josie's family is appalled when she ends her engagement to work at a local mechanic’s shop. They all assume she’s still in love with her high school boyfriend. Gabe is heir to a billionaire but he’s also charming and conservative. Acceptable.
It’s too bad the only man she has eyes for is his brother, tattooed, Mohawked mechanic Zachary Marshall. She’s tried to get his interest before but he only sees her as "Gabe’s girl”.
Which means to convince him she’ll have to put it all on the line.