Car companies don't usually design these things; heck, most don't design many of the parts of vehicles.
Everything is offloaded to third-party car part manufacturers who make things to an OEM spec (and later supply replacement components to the repair and maintenance market) - but in many cases they also supply their own parts, which can be picked and chosen by the manufacturer.
In the case of infotainment, the standard unit is DIN size; usually double-DIN for most systems today (hidden behind the plastic dash panels); the parts manufacturer designs and builds a number of components and units for that (along with software and such), and the car manufacturer picks it out of a catalog (if there's something that will work). Otherwise a more customized option is done (and then back to your comment of course).
This applies to engines, drivetrains, and virtually every other component of the car, with the exception of the frame and bodywork (interior and exterior) - though even there the part manufacturers lend their hands and expertise to the task, because they have to supply replacement components for those items as well usually.
Many of these parts suppliers used to be wholly owned by the auto manufacturers (some still are), but more than a few are independent as well, and supply parts to various manufacturers. Others are more independent, but only supply to a single manufacturer or brand. All this is to say that an automobile manufacturer today doesn't necessarily do everything completely in-house like they used to. It is much more complicated and fragmented today.
Everything is offloaded to third-party car part manufacturers who make things to an OEM spec (and later supply replacement components to the repair and maintenance market) - but in many cases they also supply their own parts, which can be picked and chosen by the manufacturer.
In the case of infotainment, the standard unit is DIN size; usually double-DIN for most systems today (hidden behind the plastic dash panels); the parts manufacturer designs and builds a number of components and units for that (along with software and such), and the car manufacturer picks it out of a catalog (if there's something that will work). Otherwise a more customized option is done (and then back to your comment of course).
This applies to engines, drivetrains, and virtually every other component of the car, with the exception of the frame and bodywork (interior and exterior) - though even there the part manufacturers lend their hands and expertise to the task, because they have to supply replacement components for those items as well usually.
Many of these parts suppliers used to be wholly owned by the auto manufacturers (some still are), but more than a few are independent as well, and supply parts to various manufacturers. Others are more independent, but only supply to a single manufacturer or brand. All this is to say that an automobile manufacturer today doesn't necessarily do everything completely in-house like they used to. It is much more complicated and fragmented today.
At least, that is how I understand it.