That's outside the car makers' control.

The public charging stations in my town (in Germany) are powered (hooked up to our common electricity network, but in terms of energy bought for them) using hydro power from a nearby river.

Any car owner could use their own generator using coal or oil to power their private charging point though. Generally speaking the only remedy to that is to make CO2 intensive power cost prohibitive. Our government decided just today to attach a CO2 tax to sales of energy sources with CO2 residues, so let's see how that develops.

Car makers don’t need to control it. Market forces are making the grid cleaner with options that blow dirty power away financially.

yes, this is a huge concern. If these cars are powered by coal or other dirty energies it doesn't make sense. Most charger networks here are powered 100% by renewables though

It still makes some sense. Granted coal rich sources will definitely make the transition worse. https://cleantechnica.com/2018/02/19/electric-car-well-to-wh...

Lifetime emissions for EVs beat ICE cars in 2-5 years [citation needed]