I was surprised to hear that Austin, TX, a fine city no doubt, had a Chipotle bus. I think Phoenix is not only a very successful city for Chipotle (48 locations, Austin has 29) but Chipotle customers would love to be able to see the truck during sporting events (I'm thinking major college games, spring training, and other events) which could only benefit the brand image of Chipotle.

See the current Chiptle truck here: http://www.chipotle.com/en-US/restaurants/lunch_truck/lunch_truck.aspx