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What Do You Think Of This Almost-Unknown Indicator Light?

We all have our roles at Jalopnik. Raph rolls cars, Travis goes out for a pack of smokes and never comes back, Patrick slaps people, Mike will do anything for $50, and I’m the Guy Who Gives A Shit About Indicator Lights. That’s why I was stunned to find out about the Slo-Lite, which I’ve never heard of before.

Illustration for article titled What Do You Think Of This Almost-Unknown Indicator Light?

The Slo-Lite, which I found in a small article in a May 1951 copy of Popular Science (my dentist really needs to get his shit together) was built by the Twentieth Century Manufacturing Company in LA. It’s a flashing amber light that gets activated (via a manifold vacuum control) whenever you let up off the gas, but before you actually brake. So, it’s like a brake light, in that it warns the drivers to your rear that you’re slowing down, but not slowing down to the degree that you’re actually braking. It’s sort of a coasting warning light.


I’m trying to decide if this would actually be useful. Assuming it was made some other color than flashing orange (so not to be confused with a turn indicator), would I find this helpful? Maybe. But, coasting doesn’t always mean slowing — on a steep hill, you can sometimes speed up while coasting, especially in a manual, out of gear or with the clutch down.

You’d also think you’d be able to tell that the car is slowing down slightly anyway, by the way you’d be, you know, getting closer to it. I suppose maybe you might think the car is just getting physically larger if you had zero understanding of three-dimensional space, and in that case the blinky light would be handy. Beyond that, I’m not so sure.

What do you think? Would this be useful, or is it forgotten and obscure for good reason?

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Great find — like many people, I had thought about such things, but I’d never heard of an actual implementation.

In a better world where other drivers paid more attention to the moving world around them, it could be useful, though these days you’d tie it to an accelerometer instead of engine vacuum. In the real world, I more and more lose hope that anything except vehicle-to-vehicle communication will save us from our various combinations of distractions, inebriations, and aggressions. Either that or short-range defensive phasers in the taillight housings.

I’ve noticed several cars lately with a center high-mounted stop lamp — the cumbersome bureaucratic term for a “third brake light” — that flashes quickly a few times when first actuated. This attention-getter may have gotten started with motorcycles. However, I think this is triggered by the same old switch as the regular brake lights; the “slowing light” function still goes begging.