Starting with the 1997 model year, we have periodically documented the influence of these technological changes on headlamp photometric performance. The three studies of tungsten halogen lamps that we have performed thus far used the same basic approach. Specifically, in these studies we measured the photometric output of the low beams for use on the 20 or 23 (depending on the study) best-selling vehicles in the Unted States and waited each vehicle's measurements with the respective sales volume to calculate the 25th, 50th, and 75th percentile market weighted values. In one additional study we obtained data for a sample of 19 HID lamps.
The present study: 1) provides new data for five HID low beams designed for use on the five best selling vehicles that offered HIDs four model year 2004, and five tungsten halogen lamps for the same vehicles; 2) examines the photometric trends from 1997 to 2004 for both tungsten halogen and HID low beams; and 3) documents a technological changes over the same time period.
", language="", issn="1057-8153", doi="", url="http://dx.doi.org/" }