A tangent, but I've always wondered what is the most efficient way to order the drop-down menus for year, make and model. Assuming your a retailer for hard to find car parts, e.g. rockauto, how do you order those menus such that someone has to do the least amount of scrolling? Year cuts down a number of defunct or newer manufacturers but Make cuts down the number of years for that same group.
I went year-make-model many years ago when I did an autoglass website.
The filtering value is big as you said, and the model year as a first filter is easy to type in, and probably gets you reasonably close if you're off-by-one. Accidentally picking an '05 Sonata instead of an '04 probably has similar parts, but if you pick Honda instead of Hyundai, you're way off in Wonderland.