I'll play devil's advocate, and speculate that the only way the i3 can be profitable is if the loss on every i3 sold is priced into the sale prices of M3's
Munro & Associates is a company that disassembles new cars to offer competitors a chance to see how they're constructed and how much they may cost to build. They also consult with major auto manufacturers in helping them design manufacturing processes that keep costs down. They recently worked with Tata Motors for the assembly design of the Jaguar i-Pace electric SUV, helping cut total manufacturing costs of the vehicle by some 30%.
Munro & Associates orchestrated a "teardown" of the i3 at its facility outside Detroit in 2015. Their report on the i3 is 23,000 pages, and can be purchased for the paltry sum of $150,000. They claim that their Cost Models are very accurate, with compiled data on major global suppliers and Tier 1, 2, and 3 manufacturers including cost calculations based on the suppliers/manufacturer’s Country of Origin, accounting for labor (OEM & Suppliers) as well as machine burden rates, utilities cost, factory floor cost, taxes and SG&A (Sales, General, and Administrative costs).
Munro engineers estimate the BMW i3 profitable at 20,000 units sold. Through the end of 2018, BMW sold 130,000 i3's.
https://www.greencarreports.com/news/1096123_bmw-i3-electric-car-teardown-profitable-at-20000-units-says-engineer-video
http://leandesign.com/pdf/BMW-i3-Prospectus.pdf