The Mercedes-Benz R-Class is cleaning up diesel a “wee” bit at a time, and it’s no “piddly” task. Mother Proof “whiz” Kristin Varela investigated this new Bluetec offering from Mercedes at the New York auto show, and in addition to finding it to be a great family car, she learned that it also ranks “No. 1” as an environmentally friendly vehicle. Watch the video to discover the magic ingredient!