Car windows squeak because the window track comes from the factory with lubricant that eventually wears off after years of use. Getting your car window to stop squeaking is a simple process and can be performed by almost anyone.
Remove the door panel below the squeaking window. Use a flat head screwdriver to carefully pop the clips from the door assembly.
Locate the power window track that the window slides past when it comes down.
Lubricate the track liberally with the window up.
Roll the window up and down a few times to make sure the lubricant is evenly distributed within the track.
Replace the interior door panel by matching the clips with the corresponding holes in the interior door edge. You may have to push it hard to pop the clip back in.
Be gentle when removing the interior door panel; you don't want to break the clips.
Be careful to not get lubricant on the power window motor or regulator. Use a stray-style spray nozzle to ensure only the window track is coated.