Let's say that now you're paying almost $30 more per gallon than you used to (based on filling up 15 gallons at $4.50/gallon whereas you used to fill it up for $2.50/gallon). Here are some items and services that you could have bought, used or otherwise engaged those $30:
Buying dinner for four at an inexpensive/fast food restaurant or dinner for two at a moderately priced restaurant
7-8 coffee drinks at Starbucks or Coffee Bean & Tea Leaf (although I hesitate to even list this since frugalistas like ourselves probably wouldn't be buying expensive coffee drinks, would we?)
Two CDs or DVDs
1.5 months of a Netflix subscription
Clothes--at a garage sale about 10-20 items; at Old Navy, maybe 4-5
The list could be endless. The point of this is that there is an opportunity cost to rising prices and I'm sure we'll be changing our behavior if we haven't already. Does it seem to you like there are fewer cars on the freeway?