When you're running a electric motor that pulls power on the magnitude of 1 * 10^5 W (i.e. 100 kW+) I doubt you care about a few extra watts total power load if you have an inefficient processor. Similarly for conventional fuel, an extra few watts on the load is hardly going to worry the alternator.
Sure an EV can suck 100kW or more of power, but only for a short time. And it can be put back into the battery via regenerative baking. Range is incredibly sensitive to electrical loads.
The reason that ARM processors are able to take so much less power than Intel is because their single threaded performance is much lower. As single threaded performance increases linearly the power required goes up as the square of that for architectural improvements and as the cube for frequency improvements modulo FO4 delays.
Intel's Atom processors haven't gotten huge amounts of love from the parent company but for DSPish code of the sort that cars are mostly running they should perform comparably to the equivalent ARM options.
I can get an off-the-shelf Xeon-D 8-core processor that runs at 35W and any single core would STOMP every ARM chip on the market. If I were to build that chip specifically for a car platform my power envelope would drop accordingly.
https://ark.intel.com/products/family/87041/Intel-Xeon-Proce...
This is an embedded application... not a gaming computer. If I move to Atom - which is what would likely be used for this sort of thing, you're talking less than 5W.
https://en.wikipedia.org/wiki/List_of_Intel_Atom_microproces...
Correct. But Atom processors performance are no better than the competition and don't currently have any of the common automotive peripherals (CAN for example).
Regardless, you're missing the point. Intel has the means to get into the space and create appropriate CPUs to compete. This acquisition makes it clear they're planning on doing just that.