And yet a Subaru was the car cited in the article as not being compliant with their regulations... it's just clear that the National Park Service doesn't understand how cars work.
I'm not sure there's anything wrong with the rule. It's easy to understand by everyone and doesn't require any additional level of testing of certification.
Realistically, people who regularly drive on these types of trails want a proper 4WD system. Not just for the "locking diff", but for the other capabilities that tend to come with a "proper" 4WD car.
Beyond "hard" capabilities, AWD torque vectoring tears roads up. The torque vectoring essentially requires the tires to spin before it will kick in. That doesn't happen in a "locked" 4wd system.
Please just stop. Where are you getting your information?
Maybe some crappy AWD systems have damaged roads at some point, I will give you the benefit of the doubt, but most do not. I've honestly never even heard of this.
4WD absolutely loses traction on roads if you leave the differential locked, and I'm sure if you amortized the extra weight and clueless drivers, 4WD does more damage then AWD.
I got rid of my 4WD truck for an AWD system specifically because the performance was better. It wasn't even close. Trucks suck compared to a Subaru in traction, and off roading for obvious reasons:
1. Trucks have no weight in the back most of the time.
2. Trucks have poor clearance.
3. Subaru's AWD is pretty danged good.
(I really didn't want to like Subarus, trust me, I looked at all the data though, and test drove everything)
Of course, none these vehicles compare to purpose built and custom off-road vehicles, but that's not what we are talking about here...
And yes, I have seen people fix the deficiencies of a truck, and have a nice cargo vehicle that climb cliffs, it's bad ass, but expensive and rare. Those trucks cost as much as a Ferrari.
And again, advanced AWD systems are more advanced and better than 4WD in every single way, and there is even more room for improvement with AWD systems. Why waste sending power down a shaft that has no traction?
Why wouldn't you want more control over more control surfaces of your vehicle?
4WD will bind and hop, but it will not cause the spinning that happens with AWD. The binding and hopping really only occurs at extreme turning angles and is extremely minor.
Torque vectoring is very good, but it’s not perfect. It require slip to detect and react. The problem is you cannot detect slippage when a wheel is completely stopped, so you have to let it spin at least a little bit. This is what causes excessive single wheel rutting.
It can also create unpredictably since you need to wait for a wheel to spin before it can kick in. Notable, if you need a lot of power, this can cause and extremely harsh jerk that does not happen in a 4WD system.
I've done Toyota Landcruiser, Toyota Tundra, Subaru Ascent, Subaru Outback, Subaru Crosstrek, Chevy Silverado.
I don't do crazy cliff stuff on them, I take my dirt bikes and quads on gnarly terrain.
The Ascent has impressed the hell out of me. Two wheels off the ground at 30% grade (40% on one corner) getting up a winding switchback in the Smokey Mountains.
If I got a citation from the National Park Service, I'd be pretty danged annoyed, and lose a lot of respect for the sensibility of the organization.
