Tesla Model S sales hit 25,202 units in the US last year

The good news is that Tesla Motors has finally answered the question that has vexed anyone trying to measure US plug-in vehicle sales. The bad news is that the US green-vehicle market appears to be slightly poorer for it. Fear not, though, as Tesla will always predict a brighter future ahead, and investors are loving the California-based electric-vehicle maker for it.

On Wednesday, Tesla released its fourth-quarter 2015 financial results, and the company, which has long resisted breaking out sales by country, said it sold 25,202 Model S vehicles in the US last year. The company used that figure as a proverbial shot across the bow of other luxury-vehicle makers by noting that Model S US sales jumped 51 percent last year while sales for competing models – like the Jaguar XJ, Lexus LS, Audi A8, and Mercedes-Benz S-Class – all fell more than 10 percent (BMW 6- and 7-Series sales fell "only" about 5 percent in 2015).

Investors liked what they heard, despite the fact that Tesla's fourth-quarter loss almost tripled from a year earlier to $320.4 million as expenses surged. Tesla shares, which had been down more than 40 percent since the beginning of the year, rose in after-hours trading the day of the announcement and almost five percent today, no doubt by Tesla chief Elon Musk's forecast of improved operating margins, increased production of the Model X, and the unveiling of the Model 3.

That said, green-car numbers took a slight hit in retrospect. Tesla had previously said its North American/overseas sales split was about 55 percent/45 percent for the Model S, implying that last year's Model S sales were at about 27,280 units. With the new figure, overall US plug-in vehicle sales, previously estimated to have fallen 6.9 percent from a year earlier, likely declined by about 8.7 percent in 2015.