This worked for me.......In a well ventilated area with NO OPEN FLAMES OR OTHER IGNITION SOURCE, use a pump up weed sprayer to apply a coating of kerosene to the entire underside of car. do this twice a day for about 4 days. By then, most of the undercoating with be softened and literally hanging off the metal surfaces. Most of it can then be removed with a plastic scraper and the rest will wipe off with a rag doing little if any damage to the existing paint. To contain the mess and protect the garage floor, I placed plastic tarps under the car before starting.