I bought an oven thermometer and left it in my car on Sept. 6.

Here's a shot of it after about 2 hours in the car.

An oven thermometer that's still in it's package with the needle point a little past 150 degrees. The gearshift of the care is beside it

A little over 150 degrees. I'm not sure what the temperature outside was, but it was no where near what it is in the middle of the summer.