It's one of the great frustrations for journalists in reporting on electric cars: Tesla Motors refuses to release its monthly deliveries of cars, unlike every other legitimate automaker.
The company now gives a global sales total every quarter, but that doesn't help in adding accurate U.S. sales for the company to the totals provided by every other volume manufacturer of plug-in electric cars.
So journalists can only report that because Tesla refuses to release its sales, comparable data is not available.
Some outlets and analysts choose to estimate (or guesstimate) the company's monthly sales, based on various metrics; others (including Green Car Reports) largely don't.
2015 Tesla Model S 70D in new Ocean Blue color
Now IHS Automotive, a longstanding industry analyst and data provider, has released a report on the electric-car maket--and it suggests that the Tesla Model S outsold the Nissan Leaf in the U.S. market during the first quarter of this year, the period from January through March.
The details of the analysis and its data, like much of the research from IHS Automotive, is available on a paid subscription basis.
If IHS is correct, that would mean that of the 10,030 Model S cars Tesla says it delivered globally from January through March, more than 4,085 were sold in the U.S.
That would represent roughly 40 percent of Tesla's global deliveries.
The number indicates that the company's largest single market continues to be North America, which includes Canadian sales of an additional 447 cars during the same period as well.
2013 Tesla Model S on ferry to Horseshoe Bay, Canada [photo: owner Vincent Argiro]
The Nissan Leaf remains the world's best-selling electric car, with the global total since December 2010 now closing in on 200,000--of which more than 82,000 have been delivered in the U.S.
Tesla hasn't released its total production figures, but along with 2,500 Roadsters, it's now estimated to have built something on the order of 90,000 Model S electric luxury sedans.
Its monthly sales could double once the upcoming Model X electric SUV is launched this fall and achieves full production.