I read in the manual for the 1984 Caprice that fuel economy gauges were options for cars at the time, I'm guessing they are vacuum gauges. Have you seen them often? I haven't, Yet at least.
I have an aftermarket mileage monitor gauge located under the dash of my colony park. Probably a relic of the 70's gas crunch. It is vacuum controlled. Since the gas gauge is non-op and filling the tank to the top is not an option, that gauge is my last resort. Wayne SavedURI :Show URL SavedURI :Hide URL http://www.stationwagonforums.com/forums/newreply.php?do=newreply&noquote=1&p=295131
Yes those are nothing more than a repainted face on a vacuum gauge. The higher the gauge reads the lighter your foot. You could just get a nice in dash vacuum gauge and use that instead. Plus once you learn how to read it (you might already) you can do tune ups and carb adjustments!
These were available earlier than 1977. Below is a page out of the '75 Oldsmobile brochure. Note the "Fuel Economy Gauge" toward the lower right. While you're at it, note the "Air Cushion Restraint System" on the top right. We call these "airbags" now. Olds was well ahead of the game in offering these in the mid-70s, although they didn't really catch on industry-wide until a decade or so later. For '75 and that general time period, airbags were optional, not standard, and only on some models.
I installed 3 round Autometer gauges on my '87 Fiero. Oil pressure, amps, and air/fuel ratio. The air/fuel gauge read its input from the ECM. It didn't really do anything useful except fill a hole in the panel and look cool.
So when you're sitting, idling in bumper-to-bumper traffic, that thing is telling you that you are getting maximum economy when in fact you are getting exactly 0 MPG. :16suspect1:
This is hardly a drawback. Many modern cars have information displays that include both average and instantaneous MPG readings. Obviously the instantaneous ones will read zero when idling, but that doesn't mean they're not useful when you're moving. With vacuum-based fuel economy meters, which are also instantaneous read-outs, you just have to be smart enough to realize that they're only useful when the car is in motion.
Many vehicles in the 1960s and 1970s offered vacuum gauges. Ford called theirs a Fuel Sentry in the 70s. Chrysler called it a Performance Indicator in the 60's A- and B-bodies. I remember the round gauge Caprices and Parisiennes could have it to the right of the speedometer. My Uncle John's '87 Safari had one. I almost bought a mauve metallic '84 Caprice sedan back in '97 that had one. It's high on my, "things to add to a vehicle once I get one worth keeping for a while" list. If I couldn't find a factory gauge I would grab any old vacuum gauge on eBay or a flea market and make a face for it to match. Put it in the clock delete hole, or somewhere else fitting. For my Torino I thought about refacing one from a 1965 Chevrolet Impala SS because it would fit well sizewise in the clock delete hole.
My, These are educational responses. Thanks. I do think a vacuum gauge is helpful in such a car, And on subject of that Oldsmobile ad now I know of those lights for the key holes.
The Lighted Key hole is an option I have never seen before. Right up there with the 69 GTO I had years ago, had optional Fiberoptic indicators for the tail lights on the rear package tray. I didn't know they were stock even when I owned it! It looked like a JC Whitney add on when I owned it.
