Try putting in a tank with a water bowl/water, crickets in another bowl and some paper towels as flooring. Add a nice clean branch with some clean leaves. Basically make a mini tank for him and leave it open in the car. If he's in there, he'll find it. Watch for him every day. Be sure to let a little air in each day if it is hot out, but watch carefully because they can jump fast and out he could go.

If it is hot out put just slightly cool water in the bowl, but not cold. Mist the tank with the water too. His survival instincts should kick in and he should look for the water.

Yes, they are nocturnal.

Good luck in your search. If he's in there he will find the home and perch on the branches. Perhaps put the tank up on the seat. They like to climb.