It's cool to see 18-wheelers driving down the highway filled with lights dotting the entire trailer or huge sleeping quarters. As long as we're not stuck behind one, the fancier or more unique, whether it's the trucks colors or design, that double-take comes naturally.

Those plain semi-trucks are so boring now even though they used to be the norm. The prettier the truck, the cooler the truck, the safer it seems, at least mentally speaking, because the owner or company is willing to put money into.

So what's with those kiddie-looking slides underneath the carriage of the big rigs? Do the bottom of the trucks open up and release its contents?

SmartTruck UnderTray System via Facebook
SmartTruck UnderTray System via Facebook

According to MSN, that huge piece of orange plastic attached to the bottom of the trailer is all about aerodynamics. Semis weigh around 80,000 pounds only getting around eight miles to the gallon around four feet off the ground so anything to help with fuel efficiency as well as a smoother drive with less turbulence is a continued focus.

While the truck's rolling, a ton of air flows in to fill that space. Then that air slams into the rear wheels and axles beneath the trailer. This means the semi truck needs to work extra hard to pull the trailer down the road.

Whether it's those rounded ramps you see on the top of the truck or fins on the back of the trailer, 18-wheelers are improving their aerodynamics.

That slide-looking thing is Smart Truck's UnderTray and it splits the air flowing beneath the trailer forcing it down and away from the wheels.

16 Rockers Who Followed the American Dream and Became US Citizens

Born elsewhere, these musicians put in the work to become full American citizens for various reasons.

Gallery Credit: Allison Rapp

2024 Rock + Metal Festival + Cruise Guide

Here's your chance to see a lot of bands!

Gallery Credit: Chad Childers, Loudwire

More From PopCrush