I would like some input/advice as to the proper schema to set up vehicle mileage tracking.  I need to track the total mileage each of our company vehicles are driven each year.  All I need is year end mileage and will subtract previous years mileage from current year to get the mileage driven in current year.  Most vehicles usually have only one driver, but we do play musical vehicles every so often.  When I first started to map this our I started with the top four tables.  Then I created the "MileageJunctionT" and now I don't think I need the top two on the right.  I also need to be able to calculate any mileage used for personal use (using a percentage for that).