Automotive Industry

most US electricity is generated with fossil fuels

This is incorrect. Over the whole country on average about 60% comes from fossil fuels, but it varies massively by location and even what time of day you are charging. Note that in that list on Wikipedia you can sort by CO2 / TWh, which is the most helpful way of looking at it since they have a narrow definition of "renewables". There are other such lists of course...

So blanket statements like "well it's mostly coming from fossil fuels anyway" are simply not helpful. If you live in Vermont, Washington, Oregon, New Hampshire, Idaho and quite a few others, you are not charging your EV with much in the way of fossil fuels, and probably then only at certain times of day.

A really good way to calculate this is to find CO2 emissions per Megawatt hour in your location by time of day. Not all generators provide this, but in California for example, there is a helpful dashboard: https://www.caiso.com/TodaysOutlook/Pages/emissions.aspx

There are also efforts like https://watttime.org/ which can cycle usage based on emissions. They actually provide APIs for this data.