Recently we made two 14 hour drives out and back, taking one day off between drives. This is longer than I like to go. I did most of the driving with one 2 hr break about 5 hrs in. Usually 9 hrs is my preferred limit. Serious question- When driving and it's going to be a long day, should you precharge your coffee (drink it before the onset of fatigue) or wait until you start to fee tired to start drinking it? How to get the most bang for your buck? Or do both methods work equally good? I tend to take a big cup of coffee with me and start drinking it early in the day.