It depends on how much ripple or variation the load can tolerate - and also what the input voltage might be (AC, DC, noise). Some electronic circuits are fairly forgiving because of on board filtering/regulation - others are not. A DC motor is probably not going to be affected by much.
It depends entirely what you want to use it for, do you have a particular purpose in mind?. As you are starting with a pretty stable DC source, it's more a question of reducing noise down the HT rail than anything else. Car radio's tend to include an internal choke and decoupling capacitors in much the same circuit.
All of this sounds pretty low consumption, and they should all have their own supply regulators - the circuit you posted should be fine, in fact probably not really needed at all, but it's always as well to take care with in-car electronics