I recently sawed off my old Boxster badge leaving behind 16 year old adhesive that only laughed at Turtle adhesive remover and WD-40. Tonight I went into Oriley's and picked up a quart (40 times more than I needed) of this
https://www.amazon.com/3M-General-Purpose-Adhesive-Cleaner/dp/B00ZIM9XPI
It was actually cheaper at Oriley's. I thought I just do not need this much of this stuff....but the board says it is the best.....so;
My old adhesive was hard and would not budge, I squeezed terry cloth in the gap under the trunk to catch any that ran down and put some on the Boxster outline....then waited 5 minutes....it soaked it all up. Put some more on and waited 5 minutes. I used my fingernail and it came off so easily I was amazed. I used a brand new white terry cloth so I could see if any black paint came off....none did. After removing this old adhesive I used soapy water and good rinsing so none of this hid in the nooks and cranny's.. Now I just have the fine outline left that I will compound off and then wax well and new badge time.