The monthly report on sales of plug-in electric cars may well have come to a close this month.
General Motors, makers of the Chevrolet Bolt EV and Volt, said it will only release sales figures quarterly starting after its Tuesday release of deliveries for the month of March.
Interestingly, the company adopted an argument used by Tesla for almost a decade in refusing to release monthly data: monthly sales have too much fluctuation to be meaningful trend indicators.
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"Monthly sales are subject to many issues that make them more volatile than quarterly sales," GM explained, "including product launch activity, weather, other seasonal factors, the number of selling days and incentive activity."
The largest U.S. automaker pledged to continue what it calls its "high level of transparency on total, brand and nameplate sales, fleet mix and inventory." Tesla, on the other hand, also refuses to break down its quarterly delivery numbers by market.
With two large electric-car makers withholding useful data on monthly sales, reports like the one you're reading may become a thing of the past.
2018 Tesla Model 3
Instead, the actual numbers of new plug-in hybrid and battery-electric vehicles delivered in any given month would have to be calculated after the fact, using registration data only available by paying substantial subscription fees to companies that aggregate it from state DMVs.
In other words, electric-car fans and advocates will have less visibility henceforth as to how well the vehicles are actually selling.
From that last-of-its-kind GM sales report, we learn that 1,774 Chevrolet Bolt EVs and 1,782 Volts were sold in March, bringing their Q1 totals to 4,335 and 3,478 respectively.
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Nissan delivered 1,500 Leafs, for a three-month total of 2,545—the first time since last September it's been in four figures for the month—as it increases deliveries of the redesigned 151-mile Leaf electric car to its dealerships.
The most startling sales total for March among cars with plugs, however, was that for the Toyota Prius Prime, the 25-mile plug-in hybrid that essentially competes with the 53-mile Chevy Volt.
Toyota managed to sell 2,922 Prius Primes last month, more than one-third of all Prius hybrids sold, and a new monthly record for the model.
2017 Toyota Prius Prime, Dallas, Texas
The Prius Prime, in fact, outsold both the Chevy Bolt EV and the Volt last month, a remarkable feat.
Perhaps equally remarkable, 1,061 Honda Clarity Plug-In Hybrid sedans were sold in only its fourth full month on sale. In three of those months, it's sold at an average rate of 900 cars a month, likely putting it among the top five or six plug-in vehicles by sales.
After more than a year of selling 350 to 700 units a month, the BMW i3 delivered a higher-than-expected 991 units in March. That was almost surely helped by the plethora of $10,000-off deals offered by numerous electric utilities in conjunction with the German maker.
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Audi delivered 214 A3 e-tron plug-in hybrid hatchbacks, bringing its year-to-date total to 558, and Mitsubishi sold 373 Outlander PHEV crossover utility vehicles, bringing its total to date to 996.
Among lower-volume entries, Porsche delivered 197 Cayenne luxury plug-in hybrid crossover utilities, for a 2018 total to date of 431. Volkswagen delivered 164 e-Golfs, for a Q1 total of 540.
Sales data for Ford's pair of Energi plug-in hybrids and its Focus Electric compliance car will be released on Wednesday.
This report will be updated periodically throughout Tuesday and subsequent days as more sales results are reported.
EDITOR'S NOTE: As of May 2017, this monthly report covers only plug-in electric cars with sales of 100 units a month or more—with occasional exceptions for new models, exceptionally large changes in sales volume, or other newsworthy events.