I think there may be some misinformation in this thread. Hopefully I can clear things up without accidentally adding any more misinformation.
DRL vs. City Lights in principle:
DRL is a concept that mostly originated in North America (I think, but am not certain). It involves having a highly visible light come on automatically when the ignition is turned on and the parking brake is off. The idea behind it was that it improves the ability of others to see the cars which use DRLs and especially in sunrise/sunset/rainy conditions where people
should have their lights on but many don't bother.
These are meant to be used during the day, and they turn off then you turn on your headlights.
City Lights are a European concept which arose to deal with some areas where local laws prohibited the use of headlights through city centers. As the headlights were not in use, small bulbs were inserted into the headlight housings to illuminate the large surface area but without the intensity of the headlights. This improves the ability of pedestrians and other drivers to be able to see the cars with city lights.
These are meant to be used at night.
DRL vs. City Lights in practice:
For the majority of vehicles when DRLs were first mandated, the DRL was essentially just the high beam running on reduced voltage. This provided the benefit of a highly conspicuous beam pattern that could be seen during the day but which was not quite as blinding as high beams in the morning/evenings. In more recent years, many manufacturers have been adding DRLs as part of the turn signal assembly or a completely separate lamp all together, most of them using the high filament of a dual filament bulb or now even LED strips. The Miata was ahead of the game, because the NA Miata uses the high-filament of the turn signals.
City lights on the other hand, use a low wattage bulb in a large reflective housing, and would not be very conspicuous during the day, but would be easily visible at night if the headlights are not on.
DRLs are generally wired to come on automatically any time the ignition is on and the car is not in park, and the tail lights and sidemarkers are not on with DRLs. On most vehicles the DRLs turn off as soon as you turn on the parking lamps, but on some (like the Miata) they stay on until you actually turn on the headlights themselves.
City lights are generally wired to turn on/off with the parking lamps.
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NA Miata Specific notes:
http://danotech.com/miata/images/drl_4.jpg -- The illumination you see here is actually the "parking lamp" position for Japanese (and perhaps European?) Miatas. The Japanese market cars used two separate bulbs for turn signal and parking lamps. It uses an 1156 bulb for the turn signal and a small w5w bulb for the parking lamp. North America market cars did not have any lamps in that position. The North American cars have an 1157 bulb in the center portion of the lens which acts as both parking lamp and turn signal.
The only first generation cars which came with DRLs (to my knowledge) were the Canadian market cars.
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EDIT: Here's some Wikipedia for more reliable info:
Wikipedia entry on "Automotive Lighting" said:
Nighttime standing-vehicle conspicuity to the front is provided by "front position lamps",[15] known as "parking lamps" or "parking lights" in North America,[5] and "front sidelights" in British English.[19] Despite the UK term, these are not the same as the side marker lights described below. The front position lamps may emit white or amber light in North America;[5] elsewhere in the world they must emit only white light.[15] Colloquial city light terminology for front position lamps[20] derives from the practice, formerly adhered to in cities like Moscow, London and Paris, of driving at night in built-up areas using these low-intensity lights rather than headlamps.[21] It is now illegal in many countries to drive a vehicle with parking lamps illuminated, unless the headlamps are also illuminated.
...
Some countries permit or require vehicles to be equipped with daytime running lamps (DRL). These may be functionally-dedicated lamps, or the function may be provided by, e.g., the low beam or high beam headlamps, the front turn signals, or the front fog lamps, depending on local regulations. In ECE Regulations, a functionally-dedicated DRL must emit white light with an intensity of at least 400 candela on axis and no more than 1200 candela in any direction.[24] Most countries applying ECE Regulations permit low beam headlamps to be used as daytime running lamps. Canada, Sweden, Norway, Slovenia, Finland, Iceland, and Denmark require hardwired automatic DRL systems of varying specification depending on the specific country. DRLs are permitted in many countries where they are not required, but prohibited in other countries not requiring them.[20]
In North America, daytime running lamps may produce up to 7,000 candela, and can be implemented as high-beam headlamps running at less-than-rated voltage.[5] This has provoked a large number of complaints about glare.[25][26]
Automotive Lighting:
http://en.wikipedia.org/wiki/Automotive_lighting#Daytime_running_lamps
And there's a whole entry on DRLs:
http://en.wikipedia.org/wiki/Daytime_running_lamp
So basically city lights are an archaic supplement to parking lamps, whereas daytime running lights are exactly what they say they are.