Missouri looks as if they have about the best registration for these cars that I have seen. Whatever you do, don't look at California as a guide as they would like to do away with all cars. The SB-100 is ok, but the 500 numbers per year are a joke as they are almost impossible for the outlying areas to get into Sacramento to get one because of the phone lines being busy and the fact many DMVs still don't want to mess with it. Very few of these cars are driven enough during the year to make any noticeable contribution to our emissions problems. A few people do drive theirs a lot, but due to our weather conditions up here we don't have that many days a year that it is nice to drive them. I wish all states could come up with a way that they would accept each others registrations, but that isn't ever going to happen.
Ron