Check out this thread, Richy mentions a product somewhere that is supposed to be for removing concrete or cement off paint. 2012 A7 with Cement Splatter and Road Paint!!
The other options that come to mind would be the usual claying or using a nylon rasor blade to scrape it off and then polish afterwards.
Or maybe try this, Stoner XENIT Natural Citrus Mold Cleaner
Stoner XENIT Natural Citrus Mold Cleaner removes resins, carbon deposits, silicones, and contaminants from molds. You’ll never again be frustrated trying to remove tough gunk and grime in your home, office, garage or car. Natural citrus XENIT by Stoner removes tacky, grimy dirt so well, in most cases you can simply “wipe it away.”
Xenit is a natural precision mold cleaner used as a degreaser in the plastics and rubber molding industries. It contains Citrus 66, a highly refine extract of citrus fruit. This powerful ingredient removes greasy soil and stains that can't be removed by soap and water.
Use XENIT to quickly permanent marker, crayon and lipstick “accidents” in the car and around the home. It removes release agents, resins, carbon deposits, and other contaminants left in mold cavities.
Xenit contains more than five, different, high performance cleaners. Unlike most water-based citrus cleaners that are designed to lift and carry dirt, XENIT is formulated to break down the complex molecules found in sticky materials
. This MicroActive cleaning action gives XENIT unequaled abilities to loosen and dissolve difficult grime like tar, grease, gum and adhesives. It even removes dried latex paint if accidentally dripped on carpet, flooring, or furniture. Xenit removes shoe scuffs and heel marks from from vinyl panels and greasy dirt from fabrics and upholstery.
Save yourself hours of agony trying to remove sticky stuff with standard cleaners. Avoid wasted time spent laboring with inferior water-based products. XENIT is formulated to evaporate and dry completely, leaving behind no sticky residues or streaky soaps.
10 oz. aerosol.