I have one big dimple in the center of my plastic window and I've tried Meguairs cleaner and polisher without any luck.

 

the sun?

 

I'm unsure what you mean by "dimple" but...

I had a few tricks that I used on my 2001.

1) Try bringing a pot of water to just less than boil and pouring that over the window. That will normally bring the window back in shape.
2) Try using a hair dryer. Just make sure you keep the hair dryer moving so that you don't burn it out or burn through the top.
3) On a hot day, leave it parked out side with the windows up. You'd be amazed how hot the car will get and that will often work.

I used the hair dryer trick a lot and it worked very well for me.

Good luck.

 

park it under the sun with all the door/window closed...leave it for 4-5 hours and it should fix most of it.