rleung96b,
Can't help with your overheating problem becuse there's so many different things that could have happened to cause the loss of water. Did you notice any water on the ground when you parked? Did you notice any smoke out the tailpipe while driving? These will give some indication of where the water went.
On your milage problem. There was a fix by the dealer for certain cars and your may fall into that category. The dealer can "flash" your computer and give it an upgrade. They won't do it unless your having a problem and ask for it. To see if your computer is alreay up to the latest upgrade, get your PT up to speed on a highway and set the cruise contol on. Now tap the cruise contol lever downwards for about a half a second. Does the speed lower by 1 or 2 miles an hour? if it doesn't, you need the computer upgrade. That's one of the things the upgrade does and the easiest way to tell if you have it. Good Luck.
