Do you see the marketing lesson here? Yes, I see two. The first is the medium being used. U-Haul is getting a lot of exposure for almost free. Other than the cost of painting the back of the truck they are getting free advertising and wide distribution will thousands of trucks on the road.
The other lesson I see is product differentiation. Perhaps U-Haul charges more for their trucks than their competitors, but they are showing here why customers may want to pay more.