I am a RedLine dealer, and have sold and used about 10 cases of SI-1. I have had several customers say good things, and I have also had good results.

I used it primarely in my 86 535i and 87 528e. Both of these cars were purchased through salvage sources, and had been sitting for several months (or longer). Using 1/2 bottle per tank in the beginning, and then 1/4 bottle per tank after the first 3 or 4 tanks. When first started, both cars ran rough (especially at idle), and were down on power. Over a few weeks of driving, the idle improved very significantly, and it felt like it had more power.

The BMW guys like RedLine products

I also purchased an 86 560sel, which also had some rough idle and driveability issues (due to sitting, I think), and used the SI-1 in the same manner, but the results were not nearly as positive. Sure, it ran a little better, but that could be due to simply getting it out and driving it. I think there is a difference in the effects when used in EFI vs. CSI...

That being said, the stuff should be good for the later cars. However, in talking with MB mechanics that I trust, they say that fuel additives have never had the following in MB circles as it did with other enthusiast groups.

Just my thoughts and experiences...

-DavidL
92 500sel
86 560sel
85 535is
87 528e
82 QPorte
92 ZX11