There was a time when backyard barbeque themed product mobiles were limited to various versions of the Wienermobile. However, these days the hot dog's frequent grill-mate has begun to hit the highways promoting hamburger havens in different parts of the country.
The Westport Flea Market Bar & Grillin Kansas City, MO boasts the "best burgers in Kansas City" and to really drive the point home they created the Burgermobile, designed by Orchid Promotional vehicles with all the trimmings.
You can find them online here:
Little Anthony's Diner in Tucson, AZ is a 50's nostalgia restaurant that hosts frequent car shows. The usual standout is the diner's own Burger Car.
You can check it out at their next sock hop: