Here is an experiment we did at the National Weather Service on a mostly sunny day with a temperature probe in a parked van with the windows closed up. The air temperature was 94 F when the experiment began at 2:09 PM.
You can see that the temperture exceeds 100 F by 2:15 PM, 110 F by 2:28, and 115 F by 2:37 PM. Had this been a car with a smaller volume, the rise would have been even quicker.
The National Weather Service reminds everybody to never leave a child or animal in a closed vehicle on a sunny day. The results can become tragic quickly.