At first glance, it looks pretty much like any of the semi cabs rolling across American roadways, though the design is a little sleeker, and the name on its grille is the giveaway. Nikola’s Class 8 tractor is one of a growing number of “green” commercial vehicles, in this case, replacing a traditional diesel drivetrain with a hydrogen fuel-cell system. Trucks deliver most of America’s freight, but they also create a disproportionate share of the transportation sector’s pollution. That’s starting to change as truck makers and truck fleet operators switch to alternative hydrogen and battery drivetrain technologies.