I was recently on a 1000 trip and fuel costs were all over the map. A low of $2.85 and a high of $3.59 per gallon. I only have the standard 36 gallon capacity tank. As long as I was going to continue my drive, it was tempting to keep filling my tank until the fuel was visible at the lower cost stations. I was curious if there was any evaporative emission systems or other reasons that overfilling was a bad idea.