@matigo The iPhone 4 & 4S were horrors for overheating, being glass front & back. When I used my 4S with navigation apps, it would to get so hot internally that I had to direct airflow from the air conditioning in the car to cool it down. It wasn't uncommom for it to go into overheat mode & effectively shut down.
In the last three days I've driven over 1200 km with the iPhone SE in a LifeProof Nuud case used with various nav apps. Never at any stage did it even warm up.
// @kdfrawg