There is a local restro shop that has quite a unique way of charging for their time ($50.00 an hour) working on a vehicle. They have a time clock, and each vehicle is given a "time card". When a mechanic goes to work on a particular vehicle, he first "clocks in" to that vehicle, and "clocks out" when finished. The shop has built a large clientel and everyone I have spoke with is very happy with not only work performed but time charged.