Actually, ALL hypermilers want it hot. No, not that kind of hot (takes out the images of near naked bodies on the beach from your mind).

We are talking about hypermiling here. So when I say hot, I mean temperature.

Temperature is a big factor in hypermiling, as there is a certain temperature that the engine has to reach before achieving maximum efficiency.

On top of that, vaporized gasoline burns more efficiently as there is more surface area exposed to the spark plugs.

Another plus factor is that if you drive in a rural area - lunchtime (the hottest time of the day) is most often the least congested time on the road. Thus, allowing for full implementation of your hypermiling techniques without any danger of inciting road rage or of having another driver affect how you hypermile your way into your best mpg.

The only time a hypermiler avoids hotter temperatures is when they gas up. It does not affect how much gas you put in the tank (that is a myth) because gas pump temperatures remain somewhere around 62F (16C) in most states. But rather, you lose a precious few more drops of gas when you open the gas tank and gasoline vapor escapes - because there is simply more fuel vapor when its hotter.

In a nutshell: Drive when its hot. Gas up when its not.