The 42 volt electrical system was an industry-wide initiative proposed some years back in the as a beefed up alternative to the ubiquitous 14 volt system. (The 12 volt in standby becomes 14 during charging, so a more accurate name is 12-14 volt)

The reasoning was that the 14 volt system had reached its peak power handling capacity, and with the ever-growing amount of electronic products and electrically actuated devices, a higher voltage was required. And yes, the flywheel mounted integrated starter generator (ISG) was proposed, along with electrically assisted steering.

However, if I recall correctly, the emphazis here was the addition of features and creature comforts. Fuel economy in those days was not a big concern, with gas prices hovering slightly above $1 /gallon.

But the industry lost interest because of the cost adders.

Apparently, the system has been resurrected, rebadged, and proposed as a fuel-economy improvement.

Anyways, this is what I recall from an electronic engineer's point of view, but my memory is no longer what it used to be. Maybe Martin could add some details.

The U.S. has reached a point “where the priorities of Congress could become so distorted by politics” that it would turn its back on the next great global industry, clean power — Rhone Resch