The cost of driving a gasoline vs. an electric car across US states

Does it affect the popularity of electric cars?

Last week I looked at differences in the adoption of electric cars across US states. The gaps were large.

There are a few possible explanations for why electric cars are more popular in some states than others. Upfront costs have been expensive, so I looked at income as one factor. Another is charging availability, so I crunched the data on the number of cars per charger.

Some readers got in touch to suggest another few factors to compare: population density, the cost advantages of running an electric car and whether electric cars can be sold directly to consumers (or have to go through a “middle-man”).

Here’s part two, where I do exactly that.

If you haven’t read the previous article, I recommend reading it first.

I should also note that doing these analyses at the state level is not ideal. We’d probably learn a lot more from county or city-level data, but I haven’t seen datasets at this level of resolution.

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The cost of fuelling a gasoline car vs. an electric one

If gasoline is expensive and electricity is cheap, then you’re more incentivised to buy an electric car.

By international standards, Americans have cheap gasoline and cheap electricity. But they tend to have bigger, less efficient cars, which offsets some of the gains that would be made from inexpensive fuel.

Anyway, it’s the ratio of gasoline-to-electricity prices that matters. I ran the numbers on how much it costs to drive 100 miles in a gasoline car, versus an electric one across US states.

Here, I’m comparing the Audi A3 and the Tesla Model 3. Of course, the result will vary by the choice of cars. I thought these two models were fairly comparable and efficient within their category.¹

For gasoline prices, I’ve taken the latest regional estimates from the US EIA.

For electricity, I’ve taken residential prices by state for April 2024 from the US EIA. This means we’re assuming that cars are charged at home (which is the case around 80% of the time).

It’s cheaper to drive an electric car in every state if you charge it at home. Fast public chargers can be two to three times as expensive, so in some states, the price benefits would disappear entirely if you relied on them instead.

In the map, I’ve shown how many more times expensive it is to drive a gasoline car [here is the interactive chart]. This is based on the cost of driving 100 miles in each. A ratio of 3 would mean that it costs three times as much to drive 100 miles in a gasoline car than an electric one.

Most states are in the range of 2.5 to 4 times more expensive. But this ratio does stretch from less than 1.5, up to 5 in the case of Washington (which has expensive gasoline and very cheap electricity).

Here is an interactive version of this chart.

California is interesting: it has very expensive electricity but also high gasoline prices. Both prices can be highly variable, though, so the ratio probably swings around quite a lot. Based on recent data, the cost benefits of driving an EV are among the lowest of all states.

Of course, this analysis also assumes that you’re buying electricity from the grid. The cost profile will be different if you’re generating your own power at home from solar.

To make it easier to explore this data I’ve also made an interactive table where you can compare the cost of driving 100 miles in an Audi A3, or Tesla Model 3. The last column shows the ratio between the two.

Here is the interactive version of this table.

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Does the cost of fuel explain differences in the popularity of electric cars?

Let’s take our price ratios and plot them against the share of cars that are electric. Ideally, we would have up-to-date estimates for every state, but the latest from the US Department of Energy is the end of 2022.

You can see it in the chart below.

I don’t see any obvious trend. You might expect EVs to be more popular in states where the relative cost of gasoline is much higher, but that doesn’t seem to be the case. In fact, they’re most popular in states where the cost benefits of running an EV are less impressive.

Here is the interactive version of this chart.

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Are electric cars more popular in states where direct sales are available?

In many states in the US, automakers can’t sell their electric cars directly to consumers. They have to go through auto dealerships. So, you couldn’t buy an EV straight from Tesla, Rivian, or Audi. You’d have to buy them through a franchise dealer.

This can impact EV sales for several reasons. First, electric cars – as an emerging technology – are often not available in the volumes that would allow them to sit in dealership lots for long. As soon as they’re manufactured, they’re shipped directly to consumers. Second, people will often need more specialised advice when purchasing an EV. They’ll have questions about range, the battery, and charging. EV manufacturers can probably provide better customer service than traditional auto dealers.

The map below shows which states do and don’t allow direct sales. It comes from the Electrification Coalition.

Source: Electrification Coalition.

In the chart below I’ve grouped each state’s share of cars that are electric but their categories above.

There is clear overlap across the categories, so buying straight from the manufacturer is not the only factor affecting uptake. But, there are no states without direct sales where EVs are particularly popular. And all of the leading states have access to direct sales.

Here is the interactive version of this chart.

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Population density: the need for more localised data

Another plausible explanation is population density. I’ve plotted this against the share of cars that are electric, in the chart below.

To get some proper relationships I think you’d need to do this at a much more localised level, such as by county or city (which I don’t have EV data for). The state-level is just too broad. Nonetheless, the data is below in case you find it helpful.

Here is the interactive version of this chart.

1. The Audi A3 has an efficiency of around 32 miles per gallon. This data comes from the US Department of Energy.

The Tesla Model 3 has a rating of around 221 Wh per mile, based on figures from EV-database.org.