Those bright bluish-looking headlights in your rearview mirror may be from a high-end luxury car that came equipped with such lights. But they may also be a sign of an aftermarket modification that's technically illegal, the National Highway Traffic Safety Administration says.
Federal customs agents have seized millions of dollars' worth of shipments of high-intensity discharge (HID) conversion kits since 2009 because the kits fail to meet federal standards, according to the Specialty Equipment Market Association, a trade group that represents motor-vehicle aftermarket companies.
What federal standards are at issue? The answer gets a bit complicated, but a series of NHTSA letters to consumers has shed some light on the topic.
First, many consumers seem to be confused by the symbol "DOT" on replacement lights, including xenon or HID conversion kits.
"DOT" doesn't mean the Department of Transportation has approved the lights; rather, it's the manufacturer's own certification of compliance with federal standards, according to NHTSA. So just because a xenon or HID conversion kit is marked "DOT" doesn't mean the federal government has certified it as street-legal.
Consumers should instead look to a federal regulation, Federal Motor Vehicle Safety Standard No. 108, which specifically discusses headlight systems. Under the standard, all replacement headlamps must be able to utilize a vehicle's existing light source, NHTSA advises.
So why not just change the light source from a regular halogen system to one that works with xenon or HID lights?
Because doing so likely violates a federal law, 49 U.S.C. 30122, which prohibits a mechanic from rendering inoperative any equipment installed in accordance with a Federal Motor Vehicle Safety Standard, NHTSA says.
In short, "NHTSA has determined that it is impossible to produce HID conversion kits (converting a halogen system to HID) that would be compliant with ... FMVSS No. 108," according to SEMA, the aftermarket trade group. Of special concern is that "HID conversion kits can produce excessive glare to oncoming motorists."
Many state laws defer to these federal standards. That gives law enforcement the power to stop and issue citations for vehicles they believe contain illegal aftermarket xenon or HID lamps.
To save on the cost of xenon or HID conversion, some drivers opt to buy blue-tinted bulbs to simulate the effect of true HID lights. But some states explicitly state that headlights must emit a white light. Check with an experienced traffic attorney to make sure your car's lights are legal.