For the first time ever, the GMC HUMMER EV has been caught undergoing testing. GM-Trucks.com has a huge 48-photo gallery of what we caught, what’s notable, what’s different and what it all means for the fully electric truck coming out this fall.

Our spy photographer relayed these details:

Up until now, just about every view available of the Hummer EV has been on its own, and in a controlled, public relations context. In our first shots of the electrified Hummer undergoing tests show the EV truck sharing image-space with a prototype for the 2022 Silverado’s mid-cycle facelift, a Chevy Tahoe, and a GMC Acadia. The Hummer EV on the flatbed is being pulled by a Chevrolet 4500-6500 HD, providing some measure of comparison between the new Hummer and the commercial-grade beast. There is also some traffic around the trailered Hummer, providing further points of comparison.

Some observations of the Hummer EV prototypes recently caught testing:

• A trim piece has been removed on the front bumper to show the mounting position of a front license plate.
• Hummer EV prototypes are equipped with redesigned tailgates, adding what appears to be a new back-up camera.
• Some initial photos of the Hummer EV were missing the shark-fin-style, roof-mounted antenna, but the initial prototypes are equipped with the antenna.
• Changes are visible on the prototypes’ rear control arms.
• Prototypes showcase new running boards, which have been changed to add steel tube protection for the rocker panels.
• Side mirrors are sleeker, and different from from what was revealed on the initially-revealed Hummer EV.
• Prototype interiors are covered in camouflage, but visible details appear to have screens consistent with official Hummer EV imagery.

With all that said, check out this massive gallery of HUMMER EV Spy Shots