The 2017 Dakar Rally was held in South America in January this year, starting in Paraguay and ending in Argentina. Here's a short video clip with highlights of the truck racing class. As you watch, remember that these beasts started out as highway trucks, designed to haul freight. Humongous rebuilds later, at a cost sometimes measured in millions of dollars, they're capable of speeds exceeding 100 mph across all terrain.
I strongly recommend watching this in full-screen mode. It's pretty spectacular.
Big beasts indeed!