Is it a:

>! A plastic vacuum reservoir in an automobile?

The bigger I am, the less I will hold. No one else would be so bold.

>!  A bigger vacuum has less stuff in it.

I get comfy in the car, as we travel real far.

>! They're used to power/control [automotive parts and accessories][1].

I used to get used a whole lot. Now, nobody gives a squat.

>! They're not in as common use as they once were.

It's clear when I fail, you'll hear folks wail.

>! Some of the components that they can be used for include brakes, door locks, and ventilation systems, giving people reason to wail.

I was popular in the eighties. I sure miss my Mercedes.

>! Mercedes are well-known for these systems.


  [1]: https://en.wikipedia.org/wiki/Vacuum_pump#Applications
  [2]: https://www.google.com/search?q=mercedes%20vaccum&ie=utf-8&oe=utf-8#q=mercedes%20vacuum%20pump