Driving a concept car is usually an exercise in going slow -- many are just built to stand still and look good. Not the Chevrolet Colorado ZH2, though.

While it's technically a concept, the ZH2 is capable of functioning out in the real world. And it needs to, because the US Army will use this truck to determine the efficacy of hydrogen fuel cells in environments where the Army traditionally operates.

Yes, this is a hydrogen fuel cell vehicle. Its gas engine powertrain has been removed and replaced with a proper hydrogen fuel cell, which uses compressed hydrogen gas to generate electricity, with water as the only byproduct. Standing close to the running ZH2, I heard only a slight, high-pitched whir as the fuel cell did its thing.

It might not look like a Colorado, but there's one under there... somewhere. The ZH2 rides on a stretched Colorado frame. The bulky new body massively increases the silhouette -- this behemoth is over 6.5 feet tall and 7 feet wide. It's about as imposing as a Ford Raptor, but it's based on a midsize truck. With 37-inch off-road tires and LED lighting galore, it looks ready to tackle the tough stuff.

And tackle, it sure did. Riding on a Multimatic DSSV (dynamic suspensions spool valve) suspension borrowed from the Colorado ZR2, the ZH2 had no problem plowing over moguls, up hills and across fallen telephone poles. The suspension operated in near-silence, mimicking the electric powertrain, as if there was no real challenge. The Army will probably get a bit rougher than we did, but this initial test showed some proper capability.

The truck does more than drive through mud silently. In the trunk (it's no longer a bed) lies something called the Exportable Power Take-Off Unit. It basically turns the truck into a portable generator, offering usable electric power from the truck's fuel cell. Power grids aren't exactly common in the middle of the desert, after all.

While my time in the truck was spent getting properly dirty, this is just the beginning. The ZH2 hasn't even made it to the US Army yet, so there's plenty of life left in it. I hope the Army will actually get some work done, though -- I wouldn't blame 'em if they spent a bunch of time tossing muddy rooster tails into the air before actually putting it through its paces.