From another thread I noted that BMW is instituting some power-saving measures. Voltage to the high beams goes from 0 to 12V then back to zero, so there's about 10 milliseconds of full power then 10 milliseconds of nothing, etc. The filament doesn't have cool down enough to decrease its brightness, and it's too fast to flicker. But the result is that the average power consumption of the 2 55W high beam bulbs is decreased from 110W to 55W. Dash has low power needs, either LED or something like a cellphone display. LED corona, tail and fog lights require maybe 20% of the power of equivalent incandescent bulbs. Brake and turn signals aren't generally on all the time so they're not a constant drain, only intermittent, and they're LED too. ABS only needs power when it's actually working. OTOH all the computing power on the CANBUS probably likes juice. ISTR that I heard to allow 300W for the onboard electronics.
Even with all-incandescent bulbs I could never figure why my Goldwing needed a 1200W alternator. Maybe so I could do some roadside arc welding?
Pulsing the power to LEDs is a very common trick in the display and lighting business for decades. This is the first time I have heard of it on head lights. The human eye latches on the peak light and does not notice the off time if it is fast enough. As a result, a 50% duty cycle light can look twice as bright as 100% one, on the same power, or just as bright on half the power.