How the GMC Hummer EV's Diagonal-Driving 'Crab Mode' Works
In keeping with Hummer tradition, the new Hummer EV pickup from GMC is a massive block of a thing. Like the Ford SVT Raptor, the 2022 Hummer EV, is required by law to display identification lamps front and rear on account of its greater-than-80-inch width. It’s rides on a wheelbase an inch and a half longer than a Cadillac Escalade ESV’s and it’s five inches taller, too. But by the power of technology and a catchy marketing name and logo, the Hummer EV can effectively shrink.
One of the goals of the Hummer EV program–the reason it exists, really–was to make a truly capable off-road truck out of this electron-powered beast.
“Basically, if the Hummer can physically fit on the trail, it’ll be able to finish the trail,” boasts chief engineer Al Oppenheiser, he of Camaro fame.
To do that, to be able to go where Wranglers go, the big lug needed a little help from technology. All first-year Hummer EVs will come equipped with adjustable-height independent suspension with 13 inches of travel front and rear. The twin rear electric motors can act as a virtual locking rear differential. And the rig rides on knobby 305/70R-18 Goodyear Wrangler tires (sorry, those wheels only look like bead-lockers, the 2023 model should offer proper ones). None of that makes the Hummer any smaller, though. Enter, CrabWalk mode.
The Hummer cannot rotate its left- and right-side tires in opposite directions, like a tank, to spin around in its own shadow like the upcoming Rivian pickup truck promises to. Instead, the team at GM used an existing automotive technology, four-wheel-steering, to make the Hummer more maneuverable. Most vehicles with four-wheel-steer capability are able to rotate the rear wheels about three to five degrees to either aid in high-speed stability (when the rears turn in the same direction as the fronts) or aid in low-speed maneuverability (when the rears turn in the opposite direction). Either way, the capability has always been aimed at on-road benefits.
The Hummer EV can turn its rear wheels 10 degrees in either direction. When the rears are in phase with the fronts at low speed the truck can crab-walk out of trouble. Or at least that’s the aim. It can't drive sideways, of course, but it can move diagonally while still pointed straight ahead. Two underbody-mounted cameras (one forward facing and one rearward) will help you keep an eye on what's down below. And yes, the underbody cameras will have washers to keep the view clear. Expect to see plenty of videos of Hummers running diagonally over and around stuff by around this time next year.
But, of course, when turned in the opposite direction to the front wheels, the rear steer effectively shrinks the Hummer EV by significantly trimming its turning radius. According to Oppenheiser, the hulking Hummer has a turning radius roughly equal to that of a Tesla Model 3.
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