The bustaurant idea is an interesting one.
 
There is an open air double decker that tours around the L.A. area, it offers upscale worldy food.  (World Fare)
 
There is another in RI that has upscale foods. (Jullian’s Providence)
 
Another in Portland Oregon that does grilled cheese in a mobile diner theme
 
They are starting to pop up around the country.  It is a good mix of food truck and mobile restaurant.  The grilled cheese truck in Portland’s diner theme was quite interesting and fit with the food too.