This is incorrect. Manufacturers still frequently get sued when user error or negligence is involved. And here's the difference you always miss, when you keep making this defense over and over... Manufacturers can be successfully sued when there is no "malfunction" at all, and their product, in-fact functioned exactly as intended, but was, as you say "misused" by the end user, in some inappropriate way. The issue becomes, whether the misuse or abuse was foreseeable by the manufacturer or seller. If it was, then they can still be held liable for the damages their product causes (except gun manufacturers, apparently, which is part of my gripe), typically depending on the sufficiency of the warning labels that they put on the product itself... we're talking easily seen, big bright yellow/orange/white labels with lots of conspicuous delineations about how the product must not be used, etc.
You always say this man, and I keep pointing out to you over and over that the comparison fails because cars are intended to serve as transportation, while guns are intended to kill/maim. A gun manufacturer/seller intends for his product to be used to shoot people. It is pretty dubious that when his product is in-fact used to shoot people, that he is allowed to enjoy absolute immunity from any liability.