My '04 had the gray interior and I went with the darker (black/dark gray) carpeted floor mats. Looked great and didn't show as much dirt/stains as the lighter gray would have. My '06 has the beige interior and still I went with the darker (black/dark gray) carpeted floor mats. They look great and still wear better (show less gunk) than the beige would. If you're going with rubber, the stains wouldn't matter so then it's a matter of color preference. I like the contrast between the tan and black . . . but that's just me.

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MWBBMW
2006 X3 3.0i Highland Green Metallic, Sand Beige Montana Leather, Steptronic, Premium Pkg, Cold Weather Package, Privacy Glass, Xenon Headlights
2007 328i 6-speed, Black Sapphire Metallic, Sport package, Black Leatherette, Heated Seats, iPod & USB Adapter
If God had intended man to walk or fly, he would not have made BMWs!