Veterinarian Sits in a Parked Car for 30 Minutes to Show How Hot It Gets

I saw this on another site and they said it was 90 outside.

I agree with that, Jill. That won't harm a dog.

When my family travels during the summer or other warm times, one of us will stay in the car with our dog while the others go into restaurants.

Probably not higher than low nineties considering what the starting temp was, which for some locations is pretty typical for summer. There are various other studies found with an internet search that give that the car interior can be anywhere from 20 to 40 F higher, in some cases with the interior temperature not really depending on the outside temperature if you wait long enough. None of them seem to mention the car though, and the color of which and the type of car (e.g. how larger are the windows, how thick other parts are, etc.) might make a difference.

I suppose caution is needed unless you really know your car and have sat in it yourself in worst situations, because there are cases where even temperatures in the 70s have produced dangerous 115+ temperatures in the car.