More efficient electronics systems and electrified accessories like power steering, coolant pumps are cutting parasitic losses that put loads on an engine. Other technologies that are seeing increasingly widespread adoption are start-stop systems and smart alternators that charge the battery only during deceleration.
Because of the awareness that electric vehicles will see limited volumes in the near term, even the engines themselves are seeing new efforts to improve efficiency through new combustion technologies and downsizing. Conventional vehicles will also benefit from weight reduction and aerodynamic advances being developed for electrified vehicles.
[Source: Automotive News – sub. req.]