Did Tesla's $70,000 luxury Model S outsell the $30,000 Nissan Leaf last month?

An estimate from the electric-car site InsideEVs says it did, MarketWatch reported.

InsideEVs put the total of plug-in vehicles sold in 2014 at 119,710, which would reflect a 23 percent increase year over year since 97,501 plug-ins were sold in 2013.

In a strong month for auto sales, electric cars sold 12,874 units in December, beating the previous record of about 12,000 that was set in March, according to the InsideEVs estimate.

Of those vehicles, 3,500 were Model S sedans. If the estimate is accurate, that figure would make Tesla's electric luxury sedan both No. 1 in EV sales for the month and the top-performing electric car of any month ever.

The estimate puts Nissan Leaf sales at 3,102 vehicles in December, not too far under the model's record of 3,186 units sold in August. In 2014, the model also became the first EV to sell more than 30,000 units in a calendar year. 

InsideEVs used information in "from the ground" reports as well as American owner production and delivery dates, Jay Cole, the news site's editor-in-chief, told MarketWatch by email.

"Tesla is a pretty small piece of the automotive pie, relatively speaking, so I don't think the other industry groups follow them too closely," Cole wrote. "For us, Tesla is a big part of a very small segment, so we do."

Electric cars remain a small part of the United States auto industry as a whole, which delivered around 16.5 million vehicles last year for its best sales since 2006.

Palo Alto, Calif.-based Tesla doesn't report monthly unit sales, instead posting quarterly deliveries with its financial report each quarter. The automaker has not announced when its earnings for the last quarter of 2014 will be released.

December included some disappointments for EVs as well, with the Chevrolet Volt and Prius PHV facing slumping sales for the fourth month in a row and the Ford Focus EV selling just 53 cars even with a $6,000 price slash from two months ago. 

See Now: OnePlus 6: How Different Will It Be From OnePlus 5?