With one of the most detailed monthly sales reports of any auto brand competing in the United States, Mini revealed their March 2015 sales in a breakdown that included door counts.

Not since Volvo’s monthly report divvied up the V60’s sales by regular and Cross Country variants has a numbers addict been so pleased.

Excluding the 540 leftover niche versions of the second-gen BMW Mini – Convertible, Roadster, Clubman, and Coupe – and 1654 sales of the high-riding Countryman and Paceman, Mini’s core Hardtop model was up 429% to 3635 units in March 2015; up 319% to 8224 units in the first-quarter of 2015.

42%, or 1509, of the March sales were produced by the 4-door. Precisely four out of every ten Mini Cooper Hardtops sold so far this year were 4-doors.

The year-over-year results of the 2-door model are skewed by the fact that there was little overlap between the outgoing and incoming models. At this time last year, the 2-door’s demand had mostly dried up, as had much of the inventory. Thus, sales of that model alone are up 151% this year; up 209% in March.

But with its somewhat awkward stance and $1000 premium, the 4-door has quickly become an integral part of the Mini lineup. First-quarter sales of the 4-door were greater, albeit marginally so, than first-quarter sales of the brand’s other 4-door, the Countryman, sales of which tumbled 25% over the first three months of 2015.

As for the defunct Clubman, its monthly sales average between 2011 and 2014 of 425 units pales in comparison to this new 4-door’s early 1100-unit monthly average.

To what extent some of these 4-door buyers would be choosing the new 2-door if the 4-door wasn’t available, we can’t fully know. But assuming they wouldn’t, assuming they’re considering the 4-door because they wanted a Mini with extra cargo capacity and a usable rear seat that isn’t a Countryman, we can say the brand’s 2015 Q1 results wouldn’t look quite so impressive without the latest variant.

Mini brand sales are up 48% to 12,777 in early 2015. Excluding the 4-door, Mini sales are up 9.5% to 9483.

Timothy Cain is the founder of GoodCarBadCar.net, which obsesses over the free and frequent publication of U.S. and Canadian auto sales figures.