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What color should rear turn signals be? Last Autumn, NHTSA released tentative findings that amber (”yellow”) rear turn signals are up to 28 percent more effective than red ones, depending on the type of crash. Now they’ve released preliminary findings that vehicles with amber rear indicators are overall 5.3 percent less likely to be hit from behind than otherwise-identical vehicles with red ones. The benefit compares, says the report, to the enduring 4.3 percent crash avoidance benefit of the center 3rd brake light (CHMSL) mandated in 1986. This tippytoeing through the tulips with tentative and preliminary findings seems more than a little precious. Amber rear signals are required in Europe, the UK, Australia, Japan, China, and virtually the entire rest of the industrialized world outside North America; red ones have been banned for thirty-five to fifty years.

Data have been accumulating in favor of amber since at least the 1970s; Volkswagen’s 1977 study concluded amber signals are better—though this hasn’t stopped them equipping current American models with red ones. Twelve years ago the University of Michigan Transportation Research Institute determined that following drivers react significantly faster and more accurately to the brake lamps of a leading vehicle with amber rear signals versus red.

American regulators, alone in the world, have for decades dismissed the notion of restricting stylistic freedom with a requirement for amber, so automakers play with rear turn signal color as an insouciant styling gimmick in the NAFTA market: amber this year, red next year, back to amber at the next facelift. And not just on Tauruses, Intrepids and Silverados; current Audis, BMWs, Smarts, and Mercedes have red rear signals in America, as did the facelifted first-generation MINI.

In America, red rear turn signals can be implemented by flashing the brake lamps (steady dim for tail, steady bright for brake, flashing bright for turn), or they can be separate from the brake lamps. With combination brake/tail/turn lamps, simultaneously braking and signaling yields two-thirds of a full brake lamp indication, and a faulty lamp takes out two or three functions.

With separate red brake and turn signals, you have identical—and dueling—red lights right next to each other. The only rear lighting functions that share a color and intensity range under international ECE regulations are the brake light and the rear fog light, and the regs require their closest lit edges to be at least 10 cm (4 inches) apart. There’s no such separation requirement for brake lights and red turn signals in American regulations.

If the driver’s foot is on the brake pedal of a current Rabbit, Jetta, Passat, Sonata, X5, Q5, Accord coupe, Camry, or any of many other recent vehicles, his turn signal is practically invisible until you’re sucking his tailpipe. If he’s getting on and off the brake while signaling, just forget about unscrambling a coherent message from his rear lights in the fractional moment available at speed in traffic.

Implementing amber rear signals has never been tricky or costly or difficult, even within physical constraints. American cars were being successfully sent to Australia with amber rear signals and without ugly mutilation back when Ward and June were scolding Beaver Cleaver for leaving his bike in the rain. Back then, countries like Australia accommodated US cars with space for only two rear light colors by allowing reversing lights to be amber or white: signal for a parallel parking job, shift to reverse, and one amber light burned steadily while the one on the signal side flashed. Meanwhile, both red brake lights lit steadily. Not a bad solution, this; by dint of amber parking lights and daytime running lights, everyone in America knows that a pair of steady amber lights means you’re looking at the approaching end of the vehicle. But now, it’s tough to think of any car design that lacks ample space for red brake/tail, amber turn, white reverse, and perhaps red rear fog light functions.

Canada has long wanted to mandate amber, but is effectively handcuffed to US regulations by the threat of free-trade court action. An international effort to develop a single global lighting equipment standard based on best practices worldwide—it would have saved money and improved safety, and compliance would’ve been optional—was single-handedly killed a couple of years ago by NHTSA’s insistence that the rest of the world would have to roll back their regulations to accept red rear signals. Best practice . . . ?

But that was apparently then, and this is now: NHTSA requests public comment on their preliminary findings. Perhaps it’s time to think about admitting that the rest of the world might not have been completely out to lunch. Who knows where this could lead . . . mandatory side-on visibility of turn signals? Naw, no real benefit there. Right, NHTSA?