But the battery is currently the scarsest and most expensive part of the system. Even if the genset costs 20k (more likely 5k-10k) for tesla this is only an additional 100KWh. For MB, which seems to be at >340$/KWh if they hope to get to 220$/KWh by 2025, this would only be ~60KWh. This is still way too low for long haul. With a hybrid solution you can basically get into the market right now at a competitive price, without any of the range anxiety problems and immediately start reducing pollution. When the fully electric solution is feasible by 2020+ you can switch over with a refined Gen2 or Gen3 implementation with an already existing production line..