One of the list of terrible tasks on a 240. The stuff is almost impossible to remove completely. Seriously, there is no shortcut. When I repaint a car, I no longer bother trying to sand it smooth and then paint. I just take it off completely, prime and paint the entire door and then put fresh paint down later. It can be removed with a heat gun and spatula, but it's such a mess, and the old stuff is usually so fractured that it doesn't come up cleanly.

If you aren't re-painting, which is usually the case, mask off the door with GOOD quality, heavy masking tape. Use a vibrator sander, a jitterbug or similar, and just keep sanding carefully until you remove all of it. Take off the window sqeegee moldings, mirrors, everything that's in the way first so you can get it all. Prime and paint.

I have had some luck replacing the "anti-glare panels" with good quality, decal tape, like what the sign-makers use for logs on cars and trucks. However it's still imperative that you get the old surface clean and smooth. If you put the decal down over anything but a smooth surface, it will wrinkle and peel in short order.