According to these guys, there are 10-13 cars mechanics do not make money as well as others because they are so reliable. The usual suspects are Honda Civic, Accord, Odyssey, CR-V, Element; Toyota Camry, Corolla, Prius, Sienna; Ford Fusion and Fusion Hybrid, a couple Subaru's and Nissan Altima.
http://autos.yahoo.com/articles/autos_content_landing_pages/1520/10-cars-mechanics-hate/
http://autos.yahoo.com/articles/autos_content_landing_pages/1520/10-cars-mechanics-hate/