What is the difference between manual lock and auto lock in Dynafit Low Tech Race ski bindings?
According to this source:
Auto-locking toe lever puts you in uphill mode upon step-in, no manual lifting necessary.
What this means is you don't have to lift up the toe tab to lock in your toe manually. Racers should appreciate this because it will save a little bit of time when stepping into the skis. That being said I doubt this will be the difference that wins a race.
People will engage this lock for two reasons. The most common reason and the only official reason to engage the lock is to reduce the chance of the toe binding popping free while skinning. The alternate and not manufacturer approved reason is to increase the DIN of the bindings.
Based on the Q&A portion of the site I linked to above it appears as if the auto-locking low tech race bindings can't be used in the "unlocked" mode. Since I don't have a set of these bindings I can't attest to the veracity of this claim. It should be noted that this might be in violation of race rules, and these bindings are designed to allow lateral release with the toe locked per the link above. The relevant quotes are:
this is a grey area since the rules have been changing and the locking mechanism on the LTR is rather unique (it releases laterally at the heel even when auto-locked).
To me, the portion that you quoted means that an auto-lock is fine as long as you don’t need an additional tool in use (so the binding is self-contained/self-sufficient).
Note also this bit of text in the description (emphasis mine):
Lateral and forward release mechanisms provide a modicum of injury prevention.
While we're on the topic I think it is important to stress that I'm not encouraging people to ski all Dynafit/tech bindings with the toe locked. Unless the binding is specifically designed to be releasable with the toe locked (as it appears to be with the Low Tech Race 2.0 Auto Lock binding), you should assume "locked" means your toe will not release. There have been some tests by third parties, like Lou Dawson, that show a high DIN release with some models of Dynafit bindings with the toe locked. However, it isn't a good idea to use your gear in a manner inconsistent with manufacturer recommendations.