I've not researched on trucks as much as I have cars, so actually the 10 degrees was quite a surprise for me.The rear tires don't steer that much - the four wheel steering (4WS) section starts at 4:38, and he says in the crab mode part that the rears can only steer 10 degrees or so, which is typical of 4WS systems. Crab mode could be handy, but few of many 4WS road vehicles made so far bother to include it. GM themselves did 4WS on a previous truck - the Quadrasteer option for full-size pickups of 2002 to 2005 - and even though the 4WS system was entirely electronically controlled (no mechanical connection to the front steering), they didn't provide any manual tweaking or mode selection and just set rear steer angle based on front steer angle and road speed. Quadrasteer was capable of up to 15 degrees steering angle - a lot more than the Hummer EV allows.
My guess is the rear drive ratio is tuned for max launch torque (without overspeeding at max vehicle speed), while the front is tuned for efficiency at highway speeds.I'm still scratching my head on the differing f/b drive ratios. May be a motor efficiency cheat to where there are two drive cycle speeds they are targeting?
Yes this might be a fair reason as well, since the front gearbox is different (i.e. includes a differential) compared to the rear gearbox, and GM wouldn't want to spend millions making a specific gearbox with the same ratio as the rear just for 1 EV modelAt Tesla, the difference is the result of using a small front drive unit (designed for use with the small rear drive unit having the same reduction ratio) with the large rear drive unit (with a different motor and ratio, borrowed from the RWD variant).
In the Hummer EV, perhaps the front gearbox is shared with other coming non-truck models that are geared for a higher top speed.
