I think you should get yourself a drivers license, if you haven't got one already.
No seriously, I think the simflyers sceneries do have some catering trucks driving around: http://www.simflyers.net
. Probably the best sceneries are the Palma de Mallorca and Bremen sceneries by Oliver Pabst, which are freeware and fancy a catering truck which will dock your aircraft as well as a refueling truck (only at Bremen). Unfortunately, they are FS2000/FS2002 only.
There are cars available for download at http://www.avsim.com