Anybody who’s ever worked on a sunroof is familiar with how hot the roof of a vehicle can get. A few square feet of sheet metal acts as a nice collector and heat sink in direct sunlight.
It’s tough on thin layer of foam between the headliner fabric and the backing board, and the adhesives that hold the sandwich together. Drooping headliners are not uncommon, even though they’re serve no duty other than as decoration, and receive no direct contact or wear. Refinishing them requires an adhesive that is both strong and heat resistant.
Modern vehicle designs with steeply raked windshields result in more dashboard surface area, and more exposure to sunlight, and a dark-colored dash, as they often are, adds to that. So the glovebox, sitting below that nice heat collector, is my guess as the hottest of the candidates.
Between the center console, and under the driver’s seat, the latter sees the least exposure, and is unenclosed, so it will be the cooler of the two. The floor contains most of the sound insulation material in a car, and between it and the carpeting, is well insulated from ground heat, as well as that generated by components like the catalytic converter and the exhaust system.