Approximately when did car makers stop using two headlights (and start using one with a high beam filament)?

I’m sure that I’ve seen late-model BMW and Chevy cars with separate high/low beam headlights. And I’ve seen models from the 1970s which had single-lamp assemblies with the high and low beam filaments built into the lamp, as you suggest.

I remember it the other way around, late 1950’s single lens ( on each side ) multiple filaments. Early 1960’s every car manufacturer started using multiple lens and one of those usually has two filaments.

It was around the late 80s. I had an ‘82 Volvo that had two rectangular lights on each side. When I traded it in for a 1990, the new one had one large lens with a two filament bulb.

But now it has gotten very complicated with a bulb and lens, but also LED high beams involved. It is not consistent anymore.

I think it goes back and forth depending on what the current car designers think is cool and functional.

They used to have cars with three headlights (48 Tucker).