I am no expert but i do have an interest... so here it goes...
First thing first... Always stay with your car, much better chance of being spotted by a search party/plane or passer by...
First priority is shelter... i would use a tarp or blanket and attach it to the roof of my vehicle and then tie it to some branches for basic
Next would be to check the water supply’s (when travelling in extreme hot areas you should always carry enough for a few days) maybe try and set up
a solar still... keep an eye on wildlife, certain plants and animals can indicate that there is water nearby. Also, if you have any containers, leave
them out (a sudden tropical storm overnight could help replenish your supply)
Then build a fire for warmth... Often places of extreme heat are very cold at night... its also good for morale and helps keep spirits up (an often
overlooked part of survival is a positive mental attitude)
Try to rest during the middle of the day (to conserve water and energy)
Again shelter is first priority same as above but this time place plenty of insulation between yourself and the ground (spruce would act as a good
Also, enclose the sides of your shelter and put plenty of insulation between yourself and the vehicle. If you do not have sufficient winter clothes
then insulate the ones you do have by stuffing paper or spruce into your clothes when you sleep. Try to keep your feet and hands dry and warm... keep
your head covered to minimise heat loss.
Build a fire at the front of your shelter using long logs laid out horizontal to your shelter to maximise heat distribution (you can also build a
deflector behind the fire, out of the same logs, with some cord)... keep plenty spare to add during the night if needed... but do not build a roaring
tall fire... It will generate to much heat and burn to quickly... the aim is to get a steady warmth for long periods. If the fire is to hot you may
break into a sweat during the night... you will then become wet and run the risk of hypothermia.
For water DO NOT EAT SNOW... It will make your core temperature drop. Instead you can melt snow over your fire for water... if you do not have any
pan’s to melt the snow then build a large snowball compacted tightly(about the size of a large grapefruit) and place on a stick near the fire. Allow
this to drip into an improvised container (empty plastic first aid box, hubcap from vehicle etc...)
For both scenarios...
Set some snares away from your shelter and forage for berries (as long as you know what to look for)
Build a signal fire with lots of fast burning kindling and plenty of small dead twigs... place some larger dead sticks on top and finally add plenty
of green leaves and sticks to give off plenty of smoke.
Finally do not despair... always try to remain positive... and good luck