interior temperature

Although there might be some differential in the heat conducted from the black vs white exterior body, the overwhelming heat source is radiation and convection from the large, nearly horizontal glass fore and aft. Driving around without the A/C on a hot afternoon, I can feel the heat waves off that dash. Using a reflector on the front wind shield makes a big difference when I come out of work at the end of the day.

 

The toy doesn't have black and white auto paint on metal, and the glass enclosure keeps out the IR I spoke of, so I"m not sure the toy disproves my point.

Black auto paint doesn't come close to looking like a "black body", which reflects none of the incident radiation - thus can't be "seen" (the non-black body stuff around it can be seen). A practical example of a black body is a small hole in a hollow opaque box with interior coated with something like carbon black. The interior surfaces actually reflect some of the radiation that comes in through the hole, but only a negligible part of that makes it back out through the hole.

I suspect black body radiation heat loss is trivial compared to heat conducted to the air bathing the car.