With respect, if the bottom was firm (and I’ll bet they checked it first) then any 4wd could have done that and it’s really just grandstsnding not demonstrating capability.
I just hope it was an inland lake and not the ocean. If the ocean then it’s just bad for the vehicles.
Agree with you on the hope that it's fresh water, and I agree that it shouldn't be a problem for a "proper" 4x4 like a 70-series or a classic Defender; I'd even wager the new Defender could do it because it's specifically designed for wading. But I would suggest that very few modern 4x4s could do that depth for that length of time without risking problems; short water crossings are usually not a big deal for modern 4x4s because with the right technique, a solid bow wave keeps the "water resistant" sensitive bits - electronics like ECUs - relatively out of the wet. On a longer run like that, the bow wave is a lot less effective and water ingress around sensitive bits is a given. These sensitive bits can cause all manner of issue. A couple of examples:
- On the platform that I use (GMC Canyon/Chev Colorad), water crossings that deep and long are very likely to get water into the power steering control module which I understand is only "water resistant", not water proof. A fault in this system will cause the vehicle to enter limp home mode.
- On the Jeep JK, the ECU was at the dash level - the wading depth was stated as 33.5", but just a little bit more than that would dunk the ECU and I'm told they are not waterproof. The Gladiator (Maybe the JL too) has a second battery system that would be totally submerged in this crossing too; I know some folks have had problems with the second battery triggering a limp mode but I'm not sure if that is water related -- still, I'd be curious to see how it would do in this case because despite the Jeep being -- well, a Jeep -- it's got some aspects that are a bit more "show" than "go" and it's wading capability is part of that.
- On the Toyota Tacoma - even the off-road spec'd TRD-Pro ones - Toyota says you shouldn't do water crossings higher than the hubs of the wheels and will not cover damage caused by water crossings deeper than that; I don't know if the vehicle would do it or not but Toyota tells us not to.
So overall I don't disagree that the water wasn't a huge challenge in itself, but the above are three of the best-selling 4x4s in North America right now and I wouldn't be confident in any of them doing a longer water wade like the Gren is doing. This is more a reflection on the sorry state of the 4x4 market than anything else but it also speaks to the ability of the Gren relative to the 'competition'.