From Tesla to GM and Toyota, plug-in sales transparency has become hard to come by.

For the better part of a decade, InsideEVs has been charting the growth of electric vehicle sales in the United States. We have seen the market grow from a small collection of niche vehicles, to a bitter rivalry between the Nissan LEAF and Chevrolet Volt, to the rapid growth of the Tesla Model S and the arrival of the mass market affordable 200- mile electric vehicle kicked off by the Chevrolet Bolt.

Then this was of course followed by the unparalleled success of the Tesla Model 3, skyrocketing past 200k sales in the United States alone in less than two year’s time. A milestone still yet to be reached by any other individual model in the states.

Needless to say, this has been an exciting period of growth for the plug-in market. It is almost quaint to look back at the earliest EV charts at the beginning of this decade. Today, dozens of EVs and PHEVs have entered the market spanning almost every single vehicle category. One might expect that the industry would be touting this growth and happy to provide their sales data. But, over the past year the exact opposite has happened.

Less transparency across the board

Tesla has always been more restrictive than other automakers when it comes to providing sales data. Outside of a few rare exceptions, the electric automaker only reports data quarterly. Similarly, Tesla does not report sales by country. There are countries where accurate registration data is available and exact Tesla numbers can be charted. Unfortunately, the United States is not one of them. Some states do provide the data we need, but it is not always timely.

For this reason, our Tesla charts have always been estimates. Nothing has changed in that regard. However, in the past year, Tesla has taken two further steps to make estimating models more difficult. The big one was combining Model X and S sales data into a single number. The other major change was the announcement that moving forward Tesla will no longer be providing in-transit numbers at the end of each quarter. The first month of a quarter is often the most difficult to estimate, especially when a model launches in a new territory. No longer having this data takes away yet another tool at our disposal.

General Motors followed in Tesla’s footsteps early last year when they announced sales reporting would switch to quarterly. We put together a method of estimating Chevrolet Bolt and Volt deliveries by observing inventory data from Several times a week we would track current inventories and their increases or drops. In addition, we would take into account the amount of new inventory added over the same period of time to estimate sales numbers over the quarter.

This method proved to be quite successful after we correctly called the drop in U.S. sales of the Chevy Bolt last summer and fall following a relatively strong Q4 2017 and Q1 2018. So, we combined this method with data we had on other vehicles in order to improve their monthly estimates as well. BMW and Mercedes would provide us with a total number of plug-in vehicle sales, then we used our tracking to improve the estimate for the split for each model for instance.

But as the year went on and changed to 2019, Ford joined GM in switching to quarterly sales, then Fiat/Chrysler. Toyota used to provide splits for all Prius models so we would have exact numbers for the Prius Prime – this too has stopped and now the Prime is lumped in with all Prius sales numbers.

This quarter, we've been cut off from our inventory data source since now rounds inventory down for each 1,000 and maxes out at 2,000. CarGurus has done the same thing, maxing out at 2,000. This makes it impossible for us to estimate in this way any longer. Presumably, this was at the request of automakers.

Kia/Hyundai do not provide plug-in sales numbers for the U.S. either, so now that we are no longer estimating via, we have very little indication of what is happening with those models. Honda will provide a total figure but without the ability to track inventory, estimating the split for each model just becomes a guessing game.

BMW has stopped providing exact figures for plug-in sales each month and instead has been reporting monthly percentage drops in sales YoY for all plug-in sales. With the way things are going, it is only a matter of time before BMW ends this practice as well.

Potential changes are coming to the chart

Our hope was that we would have a partner to work with on sales by the end of quarter. Unfortunately, when it comes to plug-in sales, most other sources are in the same boat as us. While we do have one potential partner that we are hopeful about, a deal has yet to be reached and the data will likely be most useful at a quarterly breakdown rather than the monthly breakdown.

Therefore, it is very unlikely that we can continue the monthly sales chart as we have in the past. This pains me personally to see, but roadblocks are being thrown up deliberately by automakers to control their messaging. This is totally within their right to do, but has a major impact on our sales chart.  

As a result, moving forward, our Plug-In Sales chart is likely to become quarterly. For Q4 our plan is to split between Oct, Nov and Dec as best as possible once we reach the end of the quarter. Beginning in 2020 the chart will likely switch to only showing Q1, Q2, Q3 and Q4. But that does not mean all monthly sales reports are going away. And, if our potential partnership with this new data provider works out, we may be able to move forward as we have in the past, with monthly reporting.

Our expectation is that we will have monthly articles reporting sales for automakers like Mitsubishi and Nissan, who are still brave enough to provide numbers. For Tesla we will provide preliminary estimates each month so long as we can do so accurately. We will have our monthly Tesla sales recap as we have had for years. We aim for 5-10% accuracy with our Tesla sales data and adjust it end-of-quarter once Tesla releases final numbers. It is at this time that the chart will be updated. By the end of the quarter, more registration data is available and Tesla releases their quarterly global sales. If we find we can no longer accurately estimate Tesla sales we will re-evaluate.

None of this is finalized and is subject to change. Steven and I had hoped to have more detailed methodology updates by this point, but several factors are still up in the air. So we’d like to hear your opinions. How do you feel about these changes?

Many other websites have dropped automakers that don’t report monthly or dropped their monthly sales reports entirely in favor of quarterly. We feel this is the best compromise to continue offering this service to our readers while also considering the massive changes in reporting that have occurred over the past year. Let us know your thoughts in the comment section below.