I just did the headlining on a Range Rover Classic, and that was very easy to get out. What can be very frustrating is when the glue does not hold up. I have found a glue that goes to a temperature of +120 celsius, what you should really go especially when the car has a dark colour. I bought of ebay from a trimmer glue with such a spec. Everything else like 3M will come down again.
Rob