Yes. Straight line mechanical is physically capable of greater friction with the underlying surface. That would also apply to a Tesla. It would be faster with mechanical locking differentials than it is with open differentials and traction control. It's the same reason a mechanically coupled 4wd system can stop faster in a straight line on snow/ice than any traction control system (all else equal).So what you are saying is in a straight line mechanical is better? With our Tesla’s it is the other way around. Straight line traction is unbelievable, cournering is where they feel not quite up to par.
Tesla uses a standard open differential carrier - so in that respect it's no different from any traction control system. It accelerates well because it has the ability to produce a lot of power for a short period of time.
By eliminating the differential the Rivan would lose some potential for traction at the limit. Like any slip sensing electronic system one tire must exceed the threshold of motion before slip is detected and then the system adjusts. Mechanical systems can approach the threshold as a coupled system - and as a result have a higher achievable maximum system friction.
The Rivian will probably never see serious offroad use, and it will probably perform pretty well for its intended purpose. It's not a rock crawler. It's just something that will have to be accepted as a limitation of the design. The tradeoff may be enough more ground clearance that it has offsetting benefits that are more useful. Hard to say until we see them in the wild. I'd love to see them put one in the Baja 1000 or the Mint 400 or similar race.
In the end I think the success or failure of Rivian will come down to the batteries. All the rest is pretty well sorted by now. Electronic drive is pretty basic tech. Lots of factories can build a unibody car/truck. The sales pitch is promising and style wise I think they've done a good job. The nut that everyone is trying to crack is energy density and charge rate. I hope it's great. If it could pull a car trailer or a camper for 300 miles per charge and recharge in 30 minutes - I'll probably buy one myself. I'm not holding my breath though. I think we'll get there soon. Can the Rivian do it? Hopefully they'll get to production so we can find out.