Sales and margin for the most part. The sales part, I imagine it's largely a failure of successfully marketing the vehicles, but I could be wrong.
The Volt to me was largely a failure of marketing at the time. Practically no normal people I know have any clue about what the Volt was. I went to a few dealerships to look at one and most salespeople didn't have a clue about the car (common though with car sales) or didn't even have any on hand to show. There was practically zero mindshare of GM equating with hybrids; the vast majority of car buyers I knew interested in hybrids essentially only knew/cared about Toyota. With declining sedan popularity in the US the writing was on the wall.
The Bolt was seen by many US car buyers as too small of a car and often confused for the several years older PHEV Volt. The amount of normal people I've heard use Volt/Bolt interchangeably is incredibly high. The people I talked to about the Bolt EUV figured it was just a different trim level of the same car, not realizing it was a good bit bigger.
Three different cars with different capabilities and yet so many people would just think they're the same V/Bolt thing GM talked about a decade or so ago.
