Wd-40 is great for removing tar, sticker residue, gum, and a bunch of other stuff without damaging the paint. As for a long term protectant, it tends to burn off on hot surfaces and does attract a little dirt. Use it sparingly and it probably won't hurt anything.

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'06 X5 4.8is, TiAg/black, cold weather pkg., comfort seats
'07 750Li, TiAg/black, sport pkg.
'05 Ford F350 silver met./slate gray, Lariat, 6.0 PSD, CC, DRW, FX4