So, if I'm following your math correctly, I'm better off driving my diesels than an electric car in my area since our power is 90% coal-fired, even though it's one of the most efficient coal plants in the country.
Yes, an EV driven on 90% coal power spits more CO2 than a TDI, at the tail-pipe. That's assuming 3 miles per kwh and 40 miles per gallon. Bizzle brags he's getting 5 miles per kwh from his eGolf.
There's an easy, and a not so easy way to compare.
Easy:
The EV, "at the flu stack", versus the gas/diesel car's use of one gallon, or "at the tail-pipe". Here, 1 gal = 20-21lbs CO2
No so easy adds CO2 back from:
~8% loss of electric, from power plant to your house
~10% loss of electric, from house to an EV
~6kwh per gallon, to refine fuel
~CO2 release from other energy spent retrieving coal, or oil
There's a Congressional Research Study, I've linked to before, which ups the per gallon CO2 from that 20-21, to 32-36lbs, after conversions. I don't think gas/diesel powered cars do better on an all-in basis, but that's a debate that turns everyone blue in the face (how much coal in the mix, to refine the gas, etc.).
Better, more efficient, coal plants run 1600-1700lbs CO2/MWh. That's versus an average closer to 2,000lbs. As an analyst, I take 10-k disclosures for CO2 and electric output, and have ended up mathing out results like the 2,000 many times. The whole "flu-stack" window is somewhere between 1,600-2,400lbs, when you consider 50 y/o coal plants, etc.
I'm curious what utility you say is running 90% coal? Duke isn't close to that, and most these days are turning to natural gas. To boot, the Carolinas have lots of nuclear, and some of the lowest overnight electric rates one can find.