HEADLIGHTS: E1 HCR 17,5 ???

A small list to help de-crypt the hieroglyphs written on the headlight glass.

E-code: A code for which European country the light unit was type-approved.
E1 Germany
E2 France
E3 Italy
E4 Netherlands
E5 Sweden
E6 Belgium
E7 Hungary
E8 Czecheslovakia
E9 Spain
E10 Yugoslavia
E11 United Kingdom
E12 Austria
E13 Luxembourg
E14 Switzerland

HCR ? B ? HR ?
C = Dip beam.
HC = Halogen dip beam.
R = Full beam.
HR = Halogen full beam.
CR = Combined dip and full beam.
HCR = Halogen combined dip and full beam.
B = Foglight. (Dear ECE, why are the halogen foglights not called "HB"?)

10, 12,5, 20, 37,5 ?
This one is tricky. First of all, only full beam units have this code. The number refers to how many percent of 480 lux this unit emits. Previously in Europe, a car could have maximum 480 lux. But in the early nineties, new ECE regulations decreased this to 360 lux. Which is 75 % of 480. (Some fat geezer from Brüssel must have been blinded by a light-loaded truck)
This code says nothing about the light pattern, it is measured at one spot only, and therefore a full beam unit coded 17,5 can emit much more light than one coded 25.
Here's how to use these codes:
Find the code on each full beam unit. Add them together. For newer-than-ninetysomething cars, the sum must not exceed 75. For older cars, the sum must not exceed 100.
For example: My friend's -83 Opel Senator's headlights are coded "20". His aux. driving lights are coded "37,5". Let's see, …2x20, + 2x37,5, equals…err… 115. Oh, well.
Should he be pulled over by a by-the-book-asshole policeman, he can simply put the nice dust covers on the aux. driving lights, and call them "front mounted advertize posters for Bosch".
A lightunit with the dust cover on, is not necassarily defined as a lightunit…

USA vs EUROPE
By now, you've fathomed the European way of doing things. If not, click HERE. Stateside, however, legislation was a little different. And legislation may even differ from one state to another. Europe has it's E-codes. USA has a DOT stamp. European cars use a separate bulb in a (most often) designer-lightunit not legal in the states. The Americans used uni-size SAE-fit SEALED-BEAM units. In later years, more and more US cars are manufactured with DOT designer-units. For these cars to be sold in Europe, they'll have to make an E-code designer-unit aswell. Two sets of similar looking headlights for each car model? I wonder what the beancounters are saying...
Maybe this explains why so few US cars are available as RHD? That would require THREE sets of similar looking headlights for each car model. (The beancounters go frantic!)

In a sealed-beam unit there is no replaceable bulb, imagine the bulb beeing stuffed in permanently. There is no bulb-glass either, the unit's front glass doubles as a bulb-glass. So the whole unit is filled with inert gas, and sealed.
Another thing which is different from E-code lights, is the location of the filaments.The dip filament has no bulb shield! Consequently, the beam pattern is different. It has a narrow pattern which doesn't illumunate the hard shoulder further ahead, like E-code lights do. And it is tremendously weak.

This was the sole legal lightsource in the States for ages.
Later, the HALOGEN sealed-beam unit was allowed. (eightysomething, I think) This unit has a bulb! But the unit has been sealed around it, almost like the famous ship-in-a-bottle-trick. Like the H4 bulb, the tip of the "bulb" is painted black. It provides more light than a non-halogen unit, but the beam pattern stayes the same. Generally, there are two versions of every "DOT uni-size SAE-fit unit". One version provides both dip and full beam. The other one is a full-beam-only unit.

AMERICAN LEGISLATION AT ITS BEST
Canada, and some US states allow cars to have E-code lights. This is good. Motorcycles are allowed to have
E-code lights throughout the States. This is better.