Not Smart owners per se, but a knowledgeable group of car enthusiasts meeting EVERY Saturday at Sharp's Grille in Brookside -128 West 63rd Street, just east of Wornall. http://www.sharpsgrill.com/
We are guys and gals who enjoy (and many have raced) cars of all types and sizes. Formed 25 years ago under the pretentious name of "Age and Treachery Racing" we only have two Smarts so far, but our gang has owned lots of Minis, Fiats, Citroens and other sub-sub-compacts you've likely not heard of.
We gather before 8AM to compare notes (ie: show off toys and swap lies!) so we can claim our table when they open. Usually we have about 20 on any weekend. We had convinced Sharp's to open for breakfast 15 or so years back, and Marty tolerates us, and he is trying hard to expand our waistlines.
Good food, much easy parking, and great company.