Difficult to tell because of the angle, but here are a few possibilities:

http://www.myfonts.com/fonts/linotype/optima/
http://www.myfonts.com/fonts/urw/charter-oak/
http://www.myfonts.com/fonts/urw/imperial/

will check ... thanks for the quick response kthomps5

Jerry, I found a larger, less angled photo of one of their buses, and I'm pretty confident that the typeface is Charter Oak (see second link above).

Charter Oak was absolutely the correct font , kthomps5 you rock... sorry this comes so late...