I live in Las Vegas where the heat is unreal right now!! And my finances car ac just took a crap so the days he had to take me to see my ob or pick something up I got a huge cup full of ice to the top and tons of water.
A cold wet towel for your neck helps, lots of ice watet, and keep the windows down
Battery powered fan could help too. Maybe one that mists.
Water
Water
Ice
Ice.
I grab a huge cup of ice for the gas station and freeze some bottles of water for my trip every day. It help. Keep all Windows down