tandem position for best mpg

In general practice the cooler the air the more power. The cooler air is denser then hot air (same principle as hot air balloons) denser air has more oxygen. More potential power. So the denser the air the more oxygen can be inside the cylinders. But it also takes more fuel. Hence more power when cold air. It's the reverse for hotter air. It's why drag cars have lower ets in cooler temps, they can generate more power.

It's also the same basic idea behind turbos. Stuff more air into the cylinder you can add more fuel. More fuel more power. But the more fuel needs the air. It's why alot of rice burners that run a turbo make no power. They didn't add fuel. They just added air and screwed everything up.

 

It's funny, I feel like the truck pulls better when the weight is equal or there is a bit more at the end