CR previously said it would take another look at the Model 3's braking performance once the upgrade was in place, and Tesla is no doubt hoping this will earn it a recommendation (or at least, a higher review score). It's mainly just a question of whether or not this will have any positive effects for braking performance as a whole, since few drivers will have to slam on the brakes more than once in a long while.

Either way, this is an unusual solution in the automotive world. Car makers are no strangers to releasing firmware updates, but it's rare that they affect critical functionality like the brakes. This might be a hint at what driving will be like going forward -- performance traits that once seemed set in stone can change with a quick patch.