My wife gets on my case if the car gets down to its last dot. I fill up any time it's convenient once I'm below half a tank. It keeps things quieter, if you know what I mean.
The medical doctor has the right approach. You should take care of this car as you would a good horse; when it asks you for anything, give it what it asks for. This method has never once given me a hassle. ~ the math doctor ~
