Okay... Now we're on a topic that I know A LOT about. I spent 2 and a half years doing alignments on top end cars in Ponte Verde, FL. I have done Porsches, BMW, Mercedes, NSX's, and many others. I went to alignment school for Goodyear, so these I know.
Before I go into this, I just wanted to let you know that if you had anything heavy in the rear of you car, even a golf bag, you can sometimes affect the Camber on any car. And the whole "locking the plate" thing, well I have never worked on a rack that you leave the plates locked to either measure or adjust a car. The only times that the plates are locked is when you are compensating the heads of the alignment rack. After that point you have to unlock them for the car to sit as natural as possible.
Looking at your specs that you have listed...
Your car I would think is pulling to the right. If it is doing that, I would guess that is not a very hard pull on most roads and sometimes pulls harder. That would be due to road crown. That is the camber they put on roads to help the rain drain off. Most cars come from the factory with a slight pull to the left to compensate for the crown of roads. Your Camber is sitting with your left tire leaning in more than the right, so that is what's causing the pull to that direction. If a mechanic tells you that Camber will not cause a pull... HE'S FULL OF IT! If your car is pull to the left, then you are having issues with one of your front tires and swapping the two fronts will cause it to pull the other way. In that case you might be in need of some tires, and if you just got new tires, you need to swap them to check first and if the direction changes take them back and say you have a "radial pull". I really don't see what else could be causing that problem. Your Caster is the only other thing that can cause a car to pull and with yours being even, its not that. Toe will not cause a pull. If your toe is way out of wack then your steering wheel will either sit off center, or you will get bad "waves" on either the outside or inside edges of the tire.
As for your Camber issue on the rear...
If you were coming to the shop that I worked at, I would recommend trying to drive the car the way it is for a short period of time. Maybe 2 weeks, and see what kinda wear pattern you get. .04 off is kinda close and might not show a large amount of wear. If the wear is minimal, then I would let it go and maybe just swap the rear after 10,000 miles or as needed.
so that you do not wear out your tires, keep check the inside edge for excessive wear. If the tire wears quickly, then I would see about correcting it. Which being that the rear is non-adjustable, you will have to get an aftermarket kit to correct the problem.
One thing that you have to keep in mind about German made cars. They are made to have strong amounts of rear Camber. Most American mechanics will be quick to try and set the rear Camber a 0.0 to reduce the wear on the tires which only has about a 50% chance of not wearing out the outside edges of the rear tire.
If you still need some more help, just email me and we can get in discuss this better.
lod13roc@hotmail.com