Well, first off, there is reason to suspect this fatality was a knowledge failure, not a lack-of-equipment failure. Obviously we don't know the whole story, but carbon monoxide is the more probable cause.

Regarding the gear discussion: in a car, the challenge is a human calculation. You can add good gear like a sleeping bag, but will it be in the car when someone needs it? It takes up space, it's in the way, and aside from a few ETS diehards it probably won't be in the car on the extremely rare occasion when it's needed. And as discussed elsewhere, the clear consensus is that putting this sort of gear in stealthy locations, out of sight, is a really, really stupid idea.