It has been true for years: Mile for mile, it’s cheaper — generally much cheaper — to recharge an electric vehicle than it is to refuel one with an internal-combustion engine.

This is a crucial selling point of Tesla and other EV producers, especially during times like these when gas prices are rising. But this time there’s a wrinkle: While gas prices have indeed soared in the wake of Russia’s invasion of Ukraine, so have electricity prices — particularly in some parts of the U.S. that have been big markets for Tesla’s EVs.

It raises an interesting question. Is it true that it costs less to “refuel” an electric vehicle? These charts will help you find out.

First chart shows a baseline using national figures. The others use data specific to Boston and San Francisco, two markets where EVs are popular — and where electricity tends to be more expensive than the national average.

The answer in all three cases is that — even with regional surges in the price of electricity — it’s still quite a bit more expensive to fill your gas tank than it is to charge your EV’s battery.

The rise in gas prices has roughly kept up with electric rates. However, the average cost of adding 100 miles to your vehicle’s range has increased in America over the last few months relative to the price of charging an EV the same amount.

Does that mean this is likely to change? Although oil prices will likely fall as more producers produce, it is unlikely that electricity prices will increase enough to make EVs cheaper over the course of their lives than those from internal combustion.

Jeffries analyst David Kelley calculated the lifetime cost of owning an EV using February data. It is approximately $4,700 lower than an internal-combustion car. He said that cost difference is likely to increase as more EVs come to market — and as battery prices continue to fall — over the next couple of years.