I run B100 in my '81 240D and am quite happy with it. It's a commercial product that meets ASTM standards. The engine is quieter and smoother. I switched to B100 about six months ago and replaced the lines at that time to avoid any trouble later. I also changed the filters then, and they're still clear. I was expecting a ton of crud to come out of that 30-year-old tank, but so far so good.

It's $4.25 a gallon here in San Francisco, which is on par with D2. For me the lower emissions and not burning petroleum are important reasons to use biodiesel, too. I'm lucky to have it so readily available here.