Yeah but they both work from home. The biggest reason for putting mileage on the car, commuting, is now out.

A single extra charge in a month can really mess the stats up.

An average EV battery is what, around 70kWh? Add in a bit of charging losses and we'll say maybe 75kWh being generous here, and that's assuming a nearly dead battery to a full charge. Doing that every month is then 900kWh, or 0.9MWh/yr. That's ~4% of the energy usage of 21MWh/yr.

An average EV gets what, ~3.5mi/kWH? An average US car does ~12,000mi/yr. That theoretical average EV would then use ~3.5MWh. Two would be ~7. But this author is in the UK, where the average car only does ~7,500mi/yr or so or a little over 2MWh/yr. So for their two UK cars, assuming they drove an average mileage in an average EV efficiency, they would likely have used something like 4.3MWh/yr for their cars. About 20% of their total electricity usage. This drops a good bit if they're really getting closer to 4mi/kWh in efficiency, which is likely if they're not driving on many highways like one does in the US.

EV charging inefficiency typically loses 10-25% of the input energy, depending on temperature and battery level (low temps are bad, very low or high battery level also bad for efficient transfer).

That percentage of total usage is tiny, I agree.

We have one car and charge it quite often.

I just checked last month: 184kwh went into the Leaf. We used 557kwh in total (excluding the car charging).

We generated 1170kwh.

The key thing for me is the wild energy usage from the house. It’s a lot.

Edit: Your car energy usage calculation works out awfully close to what we use.