When opening a file as a normal user that does not have write access to said file (ex. a configuration file in /etc), there is no way to save the file without restarting Kate with sudo.

Reproducible: Always

Steps to Reproduce:
1. Open a file you do not have write access to.
2. Make a change
3. Attempt to save file

Actual Results:  
The following error message is displayed.

The document could not be saved, as it was not possible to write to /etc/wgetrc.

Check that you have write access to this file or that enough disk space is available.

Expected Results:  
Kate to pop up a request for the sudo password and properly save the file.

There are text editors that perform this functionality flawlessly (like sublime) and is really the only reason I do not use Kate as my default text editor.