You've probably spotted that tiny window at the bottom of a semi truck's passenger door cruising on the highway. Most people confuse this for an aesthetic finish or even a pet window. Well, this ...

Passing a semi-truck on the highway, your eyes might be more drawn to the trailer on the back than the cab pulling it — especially if its plastered with pictures of snack cakes or images of fast food.

There's no denying that semi-trucks are pretty common vehicles on today's roads. It is nearly impossible to find an urban area without one, a testament to not only how widespread they are, but to how ...