Jim:
It should be pointed out that AVGAS should NEVER be used in a car or truck engine or for that matter anything powered by similar engines. This fuel will destroy an automobile engine in short order. Will also clog the catalytic converter as your other writer stated.
I only recommend getting Jet-A [JP4–to be used in lieu of water clear kerosene] from an airport, not 100LL [100 octane leaded "avgas"]. Get yourself a battery operated pump or hand pump for this purpose and allow a stand off of at least 4 to six inches [distancing the pump drawing inlet from the bottom of the tank] if you have doubts about water or dirt. You may be able to provide your own barrels for use by the airport staff. This would allow you to simply exchange them periodically. As with anything that is obtained in this manner, "CAUTION" is paramount! Long Life, – Overhill