White wins this round. When otherwise identical cars sit in sunlight under matching conditions, white paint generally reflects more incoming solar radiation than black paint, reducing the energy absorbed by the body. Appearance has thermal consequences. Beneath a choice usually filed under taste lies a small but measurable negotiation with the sun.
The physics favors refusal. Solar reflectance describes the fraction of sunlight a surface sends back, while absorptance describes the fraction it takes in and can convert into heat. Black usually absorbs more. As the body warms, conduction carries heat through materials, while convection and thermal radiation help exchange energy with the cabin and surrounding air. Paint is not destiny. Glazing, upholstery, insulation, wind and parking orientation also influence cabin temperature, so a cooler exterior does not translate into a fixed temperature advantage inside. The label needs scrutiny. Visible color alone cannot fully describe a coating's response to sunlight, because pigments can differ in how strongly they reflect near-infrared radiation.
White offers no immunity. Sunlight passing through windows heats interior surfaces, and neither a pale roof nor reflective bodywork makes a parked vehicle safe for children or pets. Shade deserves more credit. For buyers comparing the same model with the same interior, choosing white can reduce solar heat gain, but seeking shade and using appropriate window shades address other routes by which heat enters. Comfort remains a system. Against the polished black door and the white one beside it, sunlight makes no judgment of elegance; it merely divides into what returns and what stays.