Have read thru all the adhesive posts without finding a solution. My black BMW is kept in heated storage. Discovered a roof leak has dissolved construction adhesive or perhaps a sealant, dripped and hardened onto the car. Quarter panel build up is about .02" thick. Floor accumulation is so hard as to resist chipping with a pocket knife. Assuming the residue is water soluble initially tried soaking with warm water. Then warm water with citrus detergent. Then straight detergent. Then tried to soften with a hot air gun. Then my standby, SEM Solve. Then Goof Off. Then resorted to rubbing compound. Nothing yielded positive results. Lastly tried a medium grit Auto Scrub sponge with their specified Glide lubricant. At first it seemed to cut well. But within a few seconds the grit was permanently fouled by residue sludge. Am at a loss to proceed. Surely someone in the trade has been down this road learning a solution.