I think you are both using different definitions of fare well.
If by fare well, we mean win a fight/keep your car against these hypothetical people, then yes (gerry), no one will fare well. If by fare well, we mean survive the carjacking and not be hospitalized/killed, then yes (jared), people succeed with that all the time.
So you guys need to figure out what outcome you're working for to have a discussion about it.
For my own input, my argument is the same. If I'm going to try to take on 3 carjackers from a seated position, the only way I'm winning that is if I've got some of captain america's super serum.
However, if I mean to survive, then most likely I'm going to survive. You could argue I need verbal de-escalation skills for that, but
A) that's not a martial art skill,
B) that's not something most security trainings actually teach well, and
C) That's not something you would really need for this particular situation (that Jared came up with). Most of the time a carjacking is occurring, people are not looking to kill the person they're stealing the car from, they're looking to take the car quickly. Especially if they're blazing weapons.