[xxs]

What would be the exact benefit for 48V?

Virtually all electronics need a step down (buck) converters as they run at lower voltages 5, 3.3, 1.8. 12V > 3.3- 1V would a single step. 48V ones would likely require an intermediate step. The only exception would be running some power systems where it'd require less current.

[AlotOfReading]

You're going to need the expensive bits of a power supply anyway to meet transient requirements, so it's not much of a savings to run at native voltage and it gives a lot of design freedom/reusability to have one voltage for everything.

The main savings is current though, because the wiring harness is one of the most expensive parts of a car.

[6SixTy]

The move to 48v is very much about efficiency within the harness backbone. For the same wattage, less amperage is needed in a higher voltage system, meaning the wires can be smaller and they produce less waste heat.

There are a few different topologies for a 48v harness, but somewhere in the line there's a 12V DC/DC converter in there somewhere.

[nickcw]

Cost.

The wiring for 48V can be a lot thinner than it is for 12V. As there is a square law involved for resistive heating it turns out that wiring for 48V can use 1/16th of the weight of copper as that for 12V.

A switchmode converter can be designed for 48V just as easily as 12V.

[op00to]

It's far cheaper and easier to just pluck a readily available 12V power supply off the shelf than it is to design one that will have limited applications outside of a single manufacturer.

[Arrath]

The inertia of established supply chains and industry norms can be a real mother to overcome.

Hobbyist computing could benefit from a move to 48V as well, if only to keep the problematic 12VHPWR from killing expensive video cards.

I say hobbyist because AIUI 48v is making inroads in server hardware but that's not my area.

[AlotOfReading]

48v automotive designs have been available from suppliers for a few years now.

You generally can't reuse non-automotive power supplies in automotive because the requirements are very different.

[bob1029]

Less copper and thinner wires throughout the vehicle.