Two biographical sources (that differ in a few details) are here and here.
Much of Phillips' work was not in the fadeaway style. I cover that in a separate post. I think that it's likely that he would have abandoned fadeaway had he lived longer, because most illustrations in that style were made around the 1910-20 decade.
Below are examples of fadeaway illustrations. Images are in chronological order; click on them to enlarge.
Phillips' earliest fadeaways were for Life magazine covers.
A more interesting design.
He also did many covers for Good Housekeeping. The model for this cover and the one above seems to be the same -- perhaps his wife.
But fadeaway was rare for his car subjects.
This seems to be painted using gouache. The reproduction process in those days obliterated the brushwork, creating a uniform surface.
Another striking design.
In the Kelly Collection of American Illustration Art.
My photo. The dark bar at the top is part of the frame.