A 2005 B5.5 is shown all other B5.5 are similar. If you feel the shaking in the entire car at idle when the transmission is in "drive", did you recently replace the axles or CV joints? Cheap rebuilt joints can fall apart and cause vibration which is carried into the body of the car. See 1000q: VW Passat CV joint to see a video showing bad joints and more details. The original idea is from MoGolf, I found that I also needed supports at the sides.
Below is a headlight removed from the car for illustration. The tabs at
the top (they were broken off) and some points at the bottom are the only things
holding the headlight in place. It's poorly supported so normal diesel
shake can cause the headlights to shake as well.
bumper removal tools
closed cell foam (won't absorb water) like weatherstripping foam or pipe insulation
Remove the front bumper. See 1000q: front bumper removal and lock carrier service position for detailed steps. You don't have to remove the lock carrier, just remove the front bumper.
Loosen the 2x T30 bolts shown below (per side) that hold the plastic
support. You will put some foam at the front bottom and at the fender
line, highlighted in green, later.
The plastic cross highlighted below is the headlight support. Move the
plastic support down and wedge some thick foam between the cross and the
headlight. Move the plastic support back up and tighten the torx bolts.
When you put the bumper back on, put a thin strip of foam along the front and
at the side-lower corner to hold the headlight in place. I found that the
side-lower corner piece was needed to keep the headlight aligned with the rest
of the bumper. Putting too much foam at the front will cause the headlight
assembly to bend back and rub against the fender. This could cause wearing
and corrosion. Even before doing this modification, one of my headlights
had already worn away the paint and had a tiny area of surface rust. If
this occurs, sand the rust away and put some anti-rust paint and a top coat of
touch up paint.
Did this work for you? Feel free to comment in at the myturbodiesel.com VW TDI discussion forum.