Yesterday I took some friends to the Querétaro International Airport, and on the way, I spotted an RTS style bus coming the oposite way. It was a dark brick-redish-brown color. It had a HUGE solar panel mounted all the way across the roof, about 15 feet back from the front. Several roof airs and a sat dish.
This is 6-lane Highway 57, between Mexico City and Querétaro, one of the most travelled in the world. I was doing about 70, and he was probably doing at least 60, so it was quick. Did not see his plates. Too much traffic! I would have LOVED to get a close-up and some pictures!