Length vs mpg, pups vs 48ft trailer. Which is better?

There are a lot of variables that affect mpg, but never heard length was one of them. However, I would say that pups will affect mpg, as the space between the pups creates more drag

 

Every wall that hits air drops mpg, but once that air is moved the continuous drag is negligent.
So a 13'6" trailer @ 28ft will be worse that a 12' @ 48ft trailer. The further the trailer is from the wall in front of it also means more air drops behind and when the next wall hits, there is more air to move. For example a super long wheelbase tractor will always get worse mpg than a tractor with the trailer tucked up next to the cab.

 

Weight is the biggest factor. Pair of doubles get less.

 

I mean if you really want to split hairs with mpg, you can get a lift axle for light loads or empty, but do you use it like that often enough to offset the cost of said lift axle?

Simple answer is no, or the mega's would use them.

 

I have pulled both 53ft stepdeck 48ft stepdeck . 53 flat and 48flat. Id say in flatbed there is no definitive answer because it changes with weight and shape of load.... I wouldnt think length would play much a factor as weight or region of country u run.

 

i honestly don’t know the math, so that may or not be true, but lift axles are definitely not idiot proof and so that alone would be a reason for the megas not to
Use them....