If you look at links below and do some basic math, you'll figure out that MB sells 85% in Europe, China and NA (NAFTA). BMW does 88% in those same countries.
I don't know if you consider 15% or 12% significant (you said market is much bigger?), but in my book what's left qualifies as a long tail, and Tesla is already present in best markets.
This is not surprising; outside of NAFTA, Europe and China, the rest of the world are either small markets, or they buy less cars and cheaper cars, or have other impediments (like Japan), so luxury and near luxury cars are much smaller percentage of overall sales. I'll stop now on this subject...
references:
2018 Global: Mercedes-Benz Worldwide Sales - Car Sales Statistics
2018 Global: BMW, Mini & Rolls Royce Worldwide Sales - Car Sales Statistics