Let me be painfully honest. I'm about as mechanically inclined as a pencil eraser. Would I date someone for their mechanical abilities? Probably so. Who knows, we might find areas of more common ground during the tune up.
Don't think you can base a relationship on just that but I think OK if it is a "fringe benefit". When we moved to the suburbs this guy I liked and had sort of a relationship with offered to rewire and modernize our electrical system. And I thought oh no what would people say? But my hub thought it worthwhile enough he didn't mind me our being together sometimes. In fact he stayed with us part of the time the work was going on.