@Dslmac2:
What oil do you use? Most firearm lubricants will not tend to dry out in any appreciable length of time. In fact, high-end gun safes even have dehumidifiers in them (to control moisture and retard rust and corrosion). Storing in a range bag versus the padded case is more a question of the padding (and protection from scratches) than one of lubricants drying out.
As far as safely storing in the car, are you more worried about the ammo cooking off or lubricants evaporating? I would suspect perhaps ammo cookoff, and if so, how hot does it get over there? I personally know of no cases where ammo has detonated due to heat while properly stored (meaning out of direct sunlight, less heat) in a car parked in the sun. Personally, I would be more concerned with someone breaking into my car and stealing the gun than I would be about the heat affecting it. I would imagine just make sure it is in a well-ventillated enclosure (not the shipping case) and you should be fine. By the way, most range bags look either like, well, range bags, or camera bags, a high-value item for thieves, and not something that should be left unattended for long.
In the Nevada high desert, summer temps can go as high as 100*+, more in direct sunlight, and I have never had problems with leaving loaded mags in the car (the gun goes with me

).
You may need to look more into humidity and salt-laden air than into the gun drying out. A good, light wipe-down with oil and good wipe off of excess should be fine. Others may even recommend no oil at all (it is, after all, a Glock), but that's just me. Inspect the gun often, and if you find the oil has attracted lint, then there is too much oil.
What kind of car do you have? Would there be a place to install a personal gun vault that is out of sight and out of direct sunlight? Perhaps that would be your answer?
Good luck!