It really depends, but it will die faster most likely. If you are streaming music/audio over LTE for example, while audio and screen information is being sent over Wifi, that obviously uses more energy than being at home on Wifi. Also since the apps you are using are running on the phone, more interaction with screen is like using your phone, minus the phone screen being on (which is a big power draw). Luckily GPS can be handled by Car's GPS.
So its not like your phone will die in one hour drive, but you could potentially put a dent in your battery.