Some cars you can. If they have a standard 1- or 2-DIN radio, or an adapter for same, then yeah you can retrofit a CarPlay-capable radio. But many newer cars

Some cars you can. If they have a standard 1- or 2-DIN radio, or an adapter for same, then yeah you can retrofit a CarPlay-capable radio. But many newer cars have totally custom, integrated audio systems and retrofitting is either extremely expensive or impossible.