> an EV is 90% efficient

An EV is 85-90% efficient with power coming out of the batteries. However, the charging efficiency of the batteries is at about 80%. So the overall efficiency is 80% of 90%, or 72%.

For the sake of replacement, we should not include the charging efficiency, because the context is that of "how kuch energy the car can store" rather than "where it comes from"

It's "how much is needed to keep doing the same thing", I don't see why charging would be excluded.

It is not about how much it can store. You cannot wish away the charging losses. There are no losses to pumping gas into a tank. Nor can you wish away the losses in the charger itself. Converting AC to DC is hardly 100% efficient.

In that case, you should also not wish away refining losses, where petroleum is turned into gasoline and other fuels.

If you want to get an accurate accounting of CO2 emissions, sure.