I look at mine all the time. I kind of make it a game to try and keep mine on the high side of 20.

Also, I read somewhere that it really isn't a vacuum gauge. On the W140 at least, it is supposed to be a comparator output of road speed vs injector pulse width.

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles