[strus]

Most of these points would apply if you use phone in your car for navigation, and most of them are not a real issue (expect being a distraction maybe).

Screen is good enough to be used in a sunny day, phone will easily reach more than 35 degrees if you play a graphics-heavy game, so this is also not an issue, battery with a battery saver mode will easily last for a few hours even if you use Google Maps all the time, and with a good mount there is a zero chance you will drop your phone and break something.

[ho_schi]

When an iPhone reaches high temperature it turns off navigation automatically. Actually newer iPhones automatically go into a low power “failsafe” mode even when not in active use. If that happens you’re only allowed to make emergency phone calls, all apps are forced off.

Source: Apples documentation and my own surprise when it did.

I don’t know much about games but assume iPhones can and will limit the core frequency before the self generated heat will be an issue. What they cannot control is the environment.