I use to own an advertising promotion, printing and sign business so I know what you are talking about when you mention advertisements in and on buses.
It is still much better viewership per dollar spend then what you had proposed. It takes very little thinking how little impact a sign on a passing personal vehicle would have either seen from above or on the street.
Unlike personal vehicles buses are constantly on the road, stop to pick up passengers, who sit inside looking at ads, and while stopped vehicles and pedestrians see the ads.
It is not a minor expense to enlarge decals to best utilize the space on your Hummer.
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