When I go grocery shopping, I store frozen items in the front trunk where the spare is and the regular groceries in the back. I've gotten a few looks placing bags on both ends of the car.
Many people have mounted audio electronics in the front trunk, and they do not seem to have a high failure rate. The air cabin vent tubes are also near the front bulkhead, so that air rushing into the vents would help to cool the area of the trunk right by the windshield. I would take a guess that you'd probably have to worry more about ambient heat on a super hot summer day with the car sitting than ambient heat caused by the car running.
With radiant heat from radiator AND the sun on it, Ill guess over 150*. The passenger compartment gets near that setting outside. Ive had plastic items melt setting on the seat or dash. The cars color would affect it to some extent too. Black getting the hottest, and white being the coolest. One reason you seen most RVs with white or silver roofs and body shells. These days you see more colors on them because they have more and better AC units.
I actually had an old cookbook made for cars with times and where to put different foods to cook them on the engine. You can cook anywhere from the air cleaner to the exhaust manifolds. Local tv news a few years ago showed them cooking eggs and bacon on a car hood outside in the sun.
Maybe I wont bring extra fuel for the power tour leg I am doing. Was thinking it'd be nice if I was stuck in a traffic jam and ran out of gas. 150 degrees is pushing it I bet for that can. Could keep it in the cabin with me, but then remove when I park and put where I wonder...
[This message has been edited by 2.5 (edited 06-11-2014).]
I keep one of those cans in the engine compartment of my jeep Cherokee right next to the quart of oil and quart of trans fluid never had a problem with any of them I know it gets hotter than 150 degrees lol
If you're doing the Power Tour, just take along a 2 gallon fuel can. Empty. You will be doing the run with lots of people and they'll usually stop to lend a hand. Keep the can in the passenger floor and as you coast to the side of the road, reach over and grab it and wave it out the window. Someone will stop to help.
A more expensive, but safe alternative is Magik Tank. 1/2 gallon emergency fuel substitute that is designed to be left in the trunk like a spare tire would be. But cheap it is not. $19.95 for a half gallon.