What we can hope for today is reusing some parts of what the automotive industry comes up with, but since their operating environment and requirements are entirely different, most of their technology can not produce a light GA engine that is better than an IO-360.
Actually, I don't agree with that statement. Electric motors are in use everywhere. From coffee grinders to trains. They're well proven and available in all shapes and sizes. Picking one off the shelf that's very suited to aviation use should be very simple. And since the motors have only very few moving parts and very predictable wear characteristics, getting them certified for aviation use should not be that hard as well. Compared to, say, a traditional piston engine consisting of upwards of 1000 components and god knows how many moving parts/bearings/friction surfaces and so forth.
It's battery technology that needs to make a giant leap for electric power to become feasible for aviation use (and automotive use as well, BTW), but the rest of the components you need for an all-electric airplane (or car) are already available, and well proven.