The lithium mining is surely not causing anywhere near as much pollution as fossil fuel burning. If you think it's actually significant, please show relevant studies and/or analysis.
BMWs are all pigfat today. Compare it to a proper sports car like a Miata.
Most cars are far too heavy and should be made lighter. Only Mazda seems to understand this and that's why the Mazda SUVs/sedans are by far the best driving vehicles in their class.
https://en.wikipedia.org/wiki/Fourth_power_law
It also simply moves the pollution to places like Africa where the extremely dirty lithium mining is externalized away from wealthy westerners.
Environmental externalization.