Monthly running cost is essentially your energy (miles ÷ efficiency × your unit rate) plus road tax (VED, currently £195 a year for an EV, about £16 a month), and from 2028 a per-mile charge on top.
Because energy is the big variable, the monthly figure swings enormously with your tariff — cheap on home off-peak, much more on public rapids. That's why we don't print one number: it would mislead most readers.
Enter your mileage and charging situation on any car page and the model gives your monthly cost now and from 2028, next to a petrol comparator, with an honest verdict. Every part of that sum is explained on the methodology page.