The AM General HMMWV (High Mobility Multipurpose Wheeled Vehicle), or Humvee, was developed for the Military in the 1980s and became an iconic fixture in the U.S. as General Norman Schwarzkopf Jr. rolled through the Iraq desert in one during the early 1990s Gulf War. Before we knew it, Arnold Schwarzenegger had one and GM bought naming rights and built the H2 from the Tahoe/Suburban platform, exuding exorbitant machismo and burning copious hydrocarbons.
Those days are long gone.
GM’s Hummer H2 last rolled down production lines in 2009 and the name synonymous with excess slowly disappeared into the horizon, sweating under the undeniably warming climate. And now the Hummer is back. GM rebirthed the Hummer name, this time as a GMC model rather than a brand. And it will emit exactly zero hydrocarbons into the air. GM thinks of it kind of like America’s first journey to the moon. You know—kind of a big deal.
Three electric motors and a floor full of batteries replace the big V8 and gas tank. Two of the three motors are mounted at the rear axle, both in the center, placed in such a way so they’re somewhat similar to a differential, with half-shafts out to the wheels. The third motor mounts in the center of the front axle. All three are about the same size and produce more or less 380 lb-ft of torque.
Before heading to the wheels, the front motor spins a single drive down gear with a 13.1:1 ratio gear and an electronically locking front differential. The rear motors spin 10:1 gears and, because each wheel has a motor, it has no diff. But through software, the drive can mimic a locking diff with torque vectoring or an open diff or whatever it wants.
And while GM’s claim of 11,500 lb-ft of torque is a bit silly, as it’s wheel torque, which is inflated compared to what we’re used to seeing, it’s more legitimate than you might think. Because you have one-speed gears, that’s the torque you have at all times. In multiple gear transmissions, you have big torque in first gear, lower in second, and so on and so forth. Regardless, total torque from the motors is still impressive. GM claims between 1,000 and 1,100 lb-ft before it reaches the torque multiplying transmissions.
Providing the necessary electrons to produce the aforementioned torque is a huge battery stored under the floor. While GM did not reveal Kwh battery pack size, the pack is made up of 24 modules claimed to give a 350-mile driving range. GM took clever packaging and wiring harness efficiencies learned from the Chevrolet Bolt and implemented them here, including a wireless battery management system. Doing it this way simplifies reconfiguring and resizing the battery pack without changing wiring harnesses. Future, less expensive Hummer EVs with smaller packs have the Bolt to thank.
But the Hummer EV goes beyond Bolt in many ways, including charging capability. GM claims charging the Hummer EV from 20 to 80 percent charge on a level two, 220 volt, system takes about 30 hours. But the pack is wired such that it’s two 12-module packs, each at 400 volts, running parallel. The system can then switch to run in series, making it an 800 volt system that can accept a 350 kw charge, the fastest currently available. GM claims you can get another 100 miles of range in 10 minutes that way.
Holding the battery in place is a big metal box also functioning as the core of the Hummer EV frame. Think of it like a steel sandwich, two rectangular plates at the top and bottom supported by vertical rods throughout. From there, sub-frames are mounted and the body is attached. But the body also incorporates structure, like a modern unit construction platform. It’s all very complex. It’s also very stiff, according to GM. And despite using several grades of high-strength steels and other “light weighting” materials, it’s going to be heavy.
With the platform, GMC installed a four-wheel independent suspension with control-arms used on both axles. Among other things, this allows for an impressive 13-inches of wheel travel. GMC then added air springs that can adjust ride by nearly eight inches. From standard ride height, the Hummer EV can drop two inches for ingress/egress and “Watts to Freedom” launch control. It also lifts two inches above standard ride height for off-road and terrain mode. GMC has also what is called extract mode, which lifts an additional four inches or six inches from standard, to help clear some gnarly terrain. Extract mode is low speed only.
If you’d rather go around instead of over something, the Hummer EV also has the most articulate rear axle steering we’ve seen, with 10 degrees of wheel movement that can operate in the same or opposite direction as the front steering. That means despite having a footprint similar to a Cadillac Escalade, it has a turning circle of a bit more than 37 feet. More like a Chevrolet Sonic.
Long story short, the GMC Hummer EV is a technological gauntlet thrown down at the other automakers. GM claims 0 to 60 mph goes by in three seconds when using its aptly named Watts to Freedom launch control. The Hummer can also handle stage 4 Moab trails, run in the desert like a Ford Raptor, and recharge like a Porsche Taycan. Oh, and it’s a convertible. Oh and full of other tech tricks.
But it’s really even more than that. GM claims the Hummer EV is being developed largely virtually, using computer aided engineering and heavy work on simulators, and that it’s being done more than two-years faster than typical development cycles. If GM pulls this off, this is nothing less than the future of the automotive industry.
Let that soak in. Wow. Moonshot indeed.
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