Cigarette lighter bulb died on me recently. There are a few threads on here about how to take them apart to replace but mostly for 147 which I think is different. So on the GT here's what I did and bulb is now successfully replaced.
1. Pull the little coin tray out and unscrew the screw below it.
2. Take the whole tray out slowly and underneath you will see the connector to the lighter.
3. push the tab in on the connector and pull it off. The tray should now be free.
4. At this point I 'thought' I had to get the metal lighter out to do the replacement. There are various descriptions of this on the forum in other threads but it's a *****. There are two 'tabs' that lock the metal barrel to to the red plastic 'lens' as it were. What I found worked for me was twisting the bottom clockwas to basically move the tabs out of the holes. I then VERY gently worked a screwdriver in between the red ring and the metal ring and then twisted and eventially the metal ring popped out. After doint this I suddenly realised for a bulb replacement it was not necessary. I include this for anyone that might need to replace the actual lighter.
5. SO, at this point metal piece is back in and we are where we were in step 3. Turn over the tray with the ligher on your left. Gently push the bottom diagonally toward the upper right corner. It should move up a bit with a click.
6. Near the base is a little plastic shield which pops off. Pop this off to expose the tab that keeps the bulb in.
7. You will see a little 'dot' that you can push in at this poing. Push this in with a small screwdriver or pen and gently pull the bulb out. Replace, reverse steps and you should be good to go!
I did take some photos which I'll try and put up later. Hope this helps keep someone else from spending too much time for a bulb! BTW the bulb you need is 12v 1.2W. I got them from here: