I am of the belief that the biggest cause of battery drain, is your signal strength. If you got a bad signal all day, your battery wont last until the drive home.
Either buy extra batteries, ( they are super cheap ), buy a car charger, or turn in the phone for another sprint phone that has trouble picking up a signal as well.
My battery gets hot as well, but only after a couple hours of being in a bad signal area.
Make sure you either reboot from time to time, or manually clear the cache to stop the running process in the background.
Also, make sure the CDMA setting is off, unless you know you are in a 4G area.