Some details that I have noticed regarding the population of the configurations

I just did some quick research on the population numbers of the configurations, which I have done two cars being the more commoner-friendly ETK 800 and the exclusive Civetta Scintilla for two polar opposites.

ETK 800: 24390 units (if including the "9500" units of the drift config), 15090 units if the drift config is normalized to other more exclusive configurations (ex. the heritage edition)

Civetta Scintilla: 4540 units

Now look at their IRL counterparts (BMW F30 and F80 M3) for the ETK 800 and the Ferrari 488 (Including the Pista and Spider) for the Civetta Scintilla.

F30 3-Series (2012-2017 only): 2,652,485 (from BMW 3 Series (F30) - Wikipedia)
F80 M3 (2014-2018): 34677 (from F80 M3 Complete Model Life Production Data (bimmerpost.com))

Ferrari 488 (2015-2019): 10000-15000 (from How Many Cars Does Ferrari Make Each Year? | Continental AutoSports Ferrari)

So in other words, the Civetta Scintilla and especially the ETK 800 are being heavily nerfed in terms of production numbers. I wonder the production numbers in BeamNG covers the entire globe of BeamNG universe, or just restricted to the few vanilla maps of towns to small-city sized areas?

 

Many possible explanations, but currently, population is currently a hidden value, used for setting spawn rates in traffic and career-mode used car listings, meaning that its functionality is entirely relative. I wouldn't be surprised if the numbers were:

A. Fudged for gameplay reasons (i.e. treated as a sliding scale of common-versus-rare rather than an absolute value)
B. Based on the US specifically (given that most of the game's vanilla maps, including its only career-compatible map so far, are set there)
C. Attempting to account for how many would be driving around or changing hands at any given moment (higher-end cars are more likely to be kept for special occasions rather than driven daily, and to be sold privately rather than on the open market)
D. Guesstimated based on what feels about right
E. Not even final yet
F. Some combination of the above

Don't forget, also, that some cars are missing variants to keep the vehicle selector somewhat usable (the D-Series, for example, would have hundreds of configs if the devs tried to replicate every version that would have been available IRL), so that could potentially also account for some of the missing population.

Still, though, 9500 sounds like a very high number for a customized, engine-swapped drift spec when the Piccolina 110A gets only 600.

Would love to hear from a dev how the numbers are chosen.