Operating manuals can be tattletales. Because information about changing incandescent lamps is mandatory, manuals have to include it if the car’s brochure says “LED taillights”, but replaceable lamps are part of the assembly. A hybrid configuration like this may be disappointing, but it’s not cause for major excitement. It would only be remarkable if the manufacturer would state a price for “Full LED taillights” and still use wolfram – as lighting specialists refer to it in their language – for certain functions. Wolfram, or tungsten, is the element used to make light bulb filaments.
In these cases, however, manufacturers regularly speak of “LED taillight” and the associated brake light. And this leads us to the most important uses of LEDs in taillights. It is what makes them especially valuable. The luminous semiconductors of the brake light give subsequent traffic about a quarter-second more reaction time. Because that’s how long it takes for an incandescent lamp to reach its full brightness. LEDs have it immediately. Their long lifetime is a real bonus, since they generally last longer than the car.
Special case: turn signals
Both advantages are secondary when it comes to the rear fog lamps. They add up to just a few hours in the lifetime of the car, if even that much. In all likelihood, the reverse lights are used more often. Yet they won’t use up the lifetime of an incandescent lamp either. What’s left are the turn signals. Except in cars of those notoriously lazy drivers who refuse to use their turn signals, these lights put in many hours of use and LEDs could be a maintenance-free option here. In the case of the orange lights, however, a technical aspect comes into play: The law specifies a function monitoring for the turn signals. One or two green lamps must indicate on the dashboard that it is blinking on the exterior. This monitoring is easy to realize with the comparatively higher power of the incandescent lamps. But LEDs require more elaborate electronics. It doesn’t cost the world, of course, but auto companies keep track of every cent.
“Residual quantities” of incandescent lamps in LED lights might be a blemish; they are not a real problem. The only reason to complain would be if the auto maker would make a claim to having “full LED”. Longlife lamps can indeed ensure nearly maintenance-free operation of turn signals. When used in turn signals, the Ultra Life lamps by Osram will likely never need replacing.