The s was sort of a wake-up call to American carmakers, who generally regarded fuel economy with about as much interest as a child regards long reports about reapportionment issues or maybe crop rotation. When people started buying Toyotas and Hondas because they got non-Paleolithic fuel economy numbers, Detroit began to pay attention. Well, a little bit of attention, at least, and a fine example of this early half-assed approach can be seen in Chrysler’s Fuel Pacer system.

I’m fond of the Fuel Pacer setup for a number of reasons. First, I have a perverse love of half-assery, and second, the system makes use of one of the most American and under-appreciated vehicular lighting details of all time: t, or turn indicator lamp.

In case you’ve — somehow — forgotten what a tell-tale style fender-mounted turn indicator lamp is, I’ll grudgingly but excitedly give you a little refresher. They’re these:

Two little lights, set far forward on the fenders, facing the driver, and given the task of informing the driver that their turn indicator is on.

They do this job in tandem with the familiar little green arrows on the instrument cluster, so they’re really pretty redundant, and I suppose are appreciated by drivers who absolutely refuse to take their eyes off the road for something as trivial as a reminder they’re indicating a turn and yet still crave visual confirmation of the act.

They’re a very American affectation, with only the Toyota Crown and a few other non-American oddballs using them, and they pretty much died out in the early 1990s.

Okay, so with that out of the way, we can dive into the whole Chrysler Fuel Pacer system. Here’s a little press explainer from when the system was released as an option across the line of Chrysler/Plymouth cars in 1975:

As you can see here, the Fuel Pacer system was, essentially, just a switch that detected engine vacuum levels. When they reached a certain point, caused by the fuel-air mixture becoming richer due to the driver pressing the accelerator pedal more, that switch would activate the driver’s side turn indicator tell-tale light.

The fundamental theory behind this sort of approach to improving fuel economy is this: making the car more fuel efficient is hard, so very hard. So let’s just try and put that burden on the driver, who does not have to be designed and built by anyone at Chrysler, and let them be responsible for good fuel economy, by visually yelling at them with a little light whenever they try to feed gasoline into the engine!

I mean, think about it. why go through the hassle of trying to develop some sort of advanced electronic engine management/control unit to keep an eye on maximizing efficiency and fuel economy when you can leverage the most wonderful ECU ever created: The human mind?

It’s all so gloriously phoned-in. You can tell they looked for the cheapest, easiest way they could implement this system.

I bet it started with an idea that they’d actually have a dashboard light dedicated to the fuel economy warning, but even that bit of extra expense and tooling and design was just too much to bear, so they looked around at what they had and realized, hey, those silly fender-mounted turn indicators are kinda redundant, and they spend most of their time doing nothing, so why not make one of those do some work for a change?

And so the Fuel Pacer System was born.

Chrysler seemed pretty pleased with the Fuel Pacer system, as it was featured quite prominently in brochures, usually shown as a glowing fender indicator light, since that’s all a driver would ever see of the system.

And, based on how people drive and how the system worked, I suspect they’d see that light an awful lot, as it would come on pretty much any time you stepped on the gas at all — so much so that I bet it didn’t take long for people to start processing it out and then ignoring it completely.

If you really did try to drive based on the scoldings of this little amber light, you’d quickly find everyone around you becoming livid and you getting frustrated at the glacially-slow sort of hypermiler-style driving you’d have to employ.

You’d likely be able to squeeze, what, 28 mpg from a Slant-6 — but at what cost?

While vacuum-based fuel economy gauges predate the system by a number of years, the idiot-light-based, minimal-effort Fuel Pacer can be thought of as the spiritual ancestor of those little green-leaf-looking ECO lights that you’ll find on the dashboards of many modern cars.

They serve the same basic purpose: to get good fuel economy by, ideally, guilting or at least nagging the driver to try and alter their habits for better efficiency.

It’s not a bad idea, really, and I’m sure for many drivers it’s helpful.