on removing the rear glass (and the front). The coupes have unique glass all around that can be difficult to find and expensive.

I have replaced the front windshield on my coupe and r&r the rear to repair a leak caused by rust-out of the channel similar to what you have. In both cases, I was pleased to have a professional glass shop do the r&r mainly for the liability and expertise.

When you remove the rear, be prepared to find your channel more rusted than you think. A competent body shop can rebuild that channel for a reasonable cost. In my case it was $200 plus $100 for the r&r. It also provided an additional level of liability since they sub-contracted the r&r to the glass shop. The major cost was the new rubber gasket. It cost more than the bodywork. If you really like the car as much as I like mine, it is worth it. Living with the leak will lead to serious rust-out problems in the trunk area.

The front windshield was replaced because of breakage. A new windshield was fairly easy to find so long as you are not hard over on factory original. The gasket on that one was not so expensive but it turns out that I did not need a new one anyway.

I get the 28mpg in combined country road and town driving although I have seen slightly over 30mpg in non-stop highway driving. It is my daily driver with 319000 miles and no sign of flagging.