Not a cross-promotional item, but a cross promotional tour... of America.

We know that Walmart in America is the home of the "Autobot Unite" toyline and the character of Hot Rod, but to really promote the Brand at their stores, they will be doing a five month cross-country visit of 870 of their stores!

The tour is split up into three teams, featuring Optimus on the East coast, Bumblebee in the Central region, and Hot Rod on the West coast... with each team only visiting stores for 3 hours, in order to fit in all those stores between June 12th and November 3rd.
(the "characters" might just be the robot suits... not the actual vehicles)