Hmmm

This happens to me a lot. Let me know if it is the same with you. It seems that when I am low on cash, my car is always either 1/4 of the way full, or on empty. When it is on empty, I put $15 of gas in, and raise the tank to about 1/4 full again. The cycle then repeats itself over and over. In contrast to that situation, when I have less bills to pay, or a bit extra money, things are different. My gas tank stays at about 1/2 to 3/4 of the way full. When I see it getting to about 1/2 full, I put $15 of gas in. The tank then raises to about 3/4 of the way full. In both of these situations, I'm spending pretty much the same amount of money on gas. Why do I do this? There are plenty of reasons, but none of them really  make complete sense.