Whenever I'm using the GPS in the car with the phone charging after about 20 minutes I get a popup message on the phones screen that's it's overheating. When I unplug the charger the message goes away.
When using the GPS the back of the phone seems to get very warm.
Yes, I had the same problem on a trip last week. First thought it was my mobile charger that was at fault (bought at Target for Samsung) and it might still be part of the cause and is going to be returned. Tried the AC charger with an inverter, seemed to work a little better, but then discovered that having the phone on the dash, in the sunlight, caused overheating quicker. Also, having a 'skin' on it to protect the phone really made it hot quick. Ended up setting the phone in front of the speedometer, out of the sunlight and then it worked good for a long time until it lost GPS signal - not sure if the phone had heated again or if signal was lost because of location of phone in car.
Chatted with Samsung and rep. did a soft reset - am going to test it again in a day or two to see what happens.
I did talk to Samsung and using the GPS does cause heat build-up in the phone; that combined with the sun beating down on the dash when the phone is typically mounted on the windshield or dash area causes significant overheating. I am in the process of building a new mount which will allow me to position the phone in front of the AC vents to keep it cooler. Also, having rubber protective case/skin on the phone adds to the problem because it does not allow the heat to escape. Hopefully positioning the phone in front of the AC without the case will solve the problem.