Bed Tool Box and MPG

Just a question for anyone that uses/have used the type of tool box that stretches across the b ed right behind the cab.

How much, if anything, does it affect the MPG of the truck?

 

Depends on what's in the box.

 

Idk I put mine on right after I got the truck.

Having the box itself there I wouldn't think would affect anything, it's gona depend how much weight you carry in it but even then I can't see it doing much.

 

Send it don’t over think it not going to affect anything

 

not affected until you put some big tools into it

 

Yeah - I don't mean by virtue of the weight of the box or anything in it. Just that I would think it would disrupt the "bubble" created by the vortex that helps with the drag of the truck.

 

Found a brief site that explains the "bubble" referred to above.
https://xplrcreate.com/2019/08/08/aerodynamics-of-tailgate-closed-vs-open/

Here, the author is using it to explain why dropping/removing the tailgate is actually bad for MPG, which is the same as what Myth Busters found years ago as well.

It seems TO ME (I may be wrong, and why I'm asking for real world experiences), the shape of the box, how there would be an air gap below, and how there would be a step to the laminar flow within the bed, would also disrupt this bubble.

 

I get it, you’re doing a deep dive into some MythBusters type logic, which I’m fully onboard with. In this case, I agree with @Taco_mikie Just go for it. If you have a need for the box, do it. If you don’t, then don’t. Weight is more of a concern than the aerodynamics. The truck is already a huge sail.

 

Actually not planning on getting a box - just a curiosity.

 

If these trucks have any beneficial aero, it's a coincidence. The square shape of the cab, the open and convoluted underside, the high ride height with larger tires that are mostly outside the body, and the open bed are all huge problems for aero. That location is tucked close to the cab inside the majority of the airflow. I bet the box matters less than opening a window or using AC. It's trivial.

 

I've never had a truck that responded (mileage-wise) to the position (or removal) of the tailgate. Tried all three variants numerous times on long freeway trips in Wyoming and North Dakota. I wouldn't expect any change from mounting a tool box or not - unless it was full of cement.