Using this definition, bullets are designed to kill people, not guns. The end does not discard the means.
Bullets are designed to kill people. Guns are designed to fire bullets. The gun is made to ease the transition of bullet from magazine to brain. A gun that cannot be used to kill people is often a useless gun (tranquillizer guns, starter pistols, veterinary guns etc aside). The gun is (in the general sense) designed to kill people.
The car is not designed to kill people. It is incidental that, post design, post production, a gun can be strapped to a car.