If you install complete compliant headlamp assemblies other than the original kind (modular self-contained compliant optics such as the Hella units, or headlamp assemblies from a different kind of vehicle, etc.), and the vehicle winds up with all required lighting and reflective functions, and they're installed such that they can be aimed correctly, you're legal. If you open up your headlamps and install optics and components (drill, cut, glue, screw, etc.) that weren't originally there, then (attempt to) reseal the headlamp, you're not. Even if the optics you install produce compliant beam patterns, by opening up your headlamp you've undone all the work to make the assembly vibrationproof, resistant to water and dirt entry, etc. And internal bezels and lenses often exert influence over the total light distribution via internal reflections, so if anything inside the headlamp changes, so does that, and you can easily get a noncompliance. Of course if you send your homemade headlamps for compliance testing and they pass, then you're legal.
I rather suspect he was discovering that with virtually the same total reflector area spread over four headlamps instead of two, the similar wattage 5.75" low beams did not perform terribly well.
But the wattage wasn't similar. The low beam of the original tungsten 5.75" high/low sealed beam headlamp #4002 was 50w, and the low beam filament was on the focal point of the reflector. Compare that to the 40w low beam filament, located above and to the left of the focal point, in the 7" high/low sealed beam headlamp #6012 -- though GE "Suburban" 7-inch sealed beams had the low beam filament on the focal point. When the 6012 was replaced by the 6014, low beam wattage went to 50 (and around the same time, #4002 was replaced by the #4000, with low beam wattage of 60).
Do some well lit European cities actually let cars drive at night with city lights alone?
"City lights" is a colloquial term. The official English term is "position lamps" (or "side lights" in England, because English cars long ago had one lamp on each side of the vehicle with a small bulb sandwiched by a colorless lens facing front and a red lens facing rear).
This was a very old practice in places like London, Paris, Moscow, Mexico City, and probably many others: headlamps were used only out in the open. In built-up areas, the "city lights" were used. It worked OK as long as streets were well lit, but the problem is obvious: the driver making their way through town will encounter lit and unlit streets, and will probably be too lazy to mess with the light switch back and forth and back and forth, so will probably just leave the "city lights" on. Woe unto any pedestrians! And I have to imagine intersections could be particularly dangerous because cars outside North America don't have side marker lights or retroreflectors. The Brits tried out a solution where if the driver switched on the "city lights" and the parking brake was released the low beams came on at half intensity -- sort of a forerunner of how some daytime running light modules are configured. They had good success with it, but the European Commission frowned on members trying to exert unique lighting requirements. Do a Google search on
"town beam" "dim-dip" and you'll come up with more info.
