On the energy tab: It says that driving a petrol car 10 miles uses 10,000 Watt-hours, eg 10 kWh.

On the costs tab, for the United States: It says that this has a cost of $0.97.

97 cents ÷ 10kWh = 9.7 cents per kWh

(I didn't look further than that. Perhaps I should have.)

---

edit: I now see a note at the very bottom stating that it is using an assumed "$0.17 for electricity".

$0.17 per kWh is plenty close enough for rough figurin', so I'd like to take this opportunity to retract my previous complaint.