Being a bit of a sad nerd, I did do some calculations along the lines of what you were discussing in the pub a couple of years ago. Based on a worse case scenario of everyone with a Tesla P80 which is a powerful electric guzzling yank tank and based on best figures I could find for miles driven per workday by all vehicles, I estimated that to charge all the cars over an eight hour night, would still need less demand on the electric grid than the grid currently supplies during the day.

All it would need is reasonable “smart” scheduling of the charging which could be done either automated or through pricing incentives just as economy7 tariffs work.

Of course majority of electric generation is still fossil fuel which in relative terms is easy to control and schedule compared to wind and solar in our climate.