That's true, but for the average person, it would be worthwhile, even with zero profit. According to my cursory internet research, the average US household spe

That's true, but for the average person, it would be worthwhile, even with zero profit. According to my cursory internet research, the average US household spends 1.5% of their annual income on car repairs[0]. The average adult works 1,300 hours per year[1]. The average household has 2.1 adults[2]. So in a five month period, the average household puts about 17 hours into car maintenance. So if you live in an average household, you'll come out on top with this scheme as long as you spend less than 17 hours on the process each time. [0] http://auto.howstuffworks.com/under-the-hood/cost-of-car-ownership/auto-maintenance-cost.htm http://auto.howstuffworks.com/under-the-hood/cost-of-car-own... [1] http://www.zerohedge.com/news/2013-05-13/how-average-american-adult-spends-24-hours-each-day http://www.zerohedge.com/news/2013-05-13/how-average-america... [2] http://www.popcouncil.us/pdfs/wp/144.pdf http://www.popcouncil.us/pdfs/wp/144.pdf