: Linear Fuel Gauge

04-27-06, 08:08 PM
Some years ago I heard that Cadillac, around 1980, did a true linear fuel gauge that when the needle showed half tank, really WAS at a half tank.

But it was dropped shortly after as people were actually COMPLAINING!!!

Anyone know when this might have occurred? And if I can get one and make it work in my 94??

Was this on V468 cars? Or?

04-27-06, 08:14 PM
I found this on a website:


Post #42

Author: MY SiR

Posted: August 22nd, 2004 at 06:09 AM

First off, this thread should be called "Fuel Consumption".

In Canada, the offical way of reporting fuel consumption is # of litres per 100 km...

On my Civic, I get about 500 km on a tank in the summer and 420 in the Winter. I usually use Shell Gold. 6th gens have 45 litre tank. 7th gens have a 50 litre tank. I believe 5th gens have a 40 litre tank. From my rough calculation I get 9.0 L/100 km

If you use Sunoco Ultra 94, you should notice worse fuel consumption numbers because of the alcohol content.

The fuel gauge is not accurate and that's how people like it. Cadillac once made an accurate and linear fuel gauge in the 80s and they had so many complaints, they were forced to change the gauge logic...

As a general rule, (and this applies for all cars):

When the car is full, the gauge is above 'F'.

When the gauge is slightly below 'F', 20-25% of the fuel has been used.

At the halfway mark, 55-60% of fuel has been used.

At about 1/4 mark, 75-80% has been used and the 'low fuel' should come on shortly after that....

Does that make sense?

Oh, spracingsports, in Cali, they use reformulated gasoline with alcohol. 250 miles sounds about right. I am assuming you usually fill up when the light comes on. You can stick to regular by the way. You have nice clean fuel down there... I think you don't drive it 'that' hard, with all the traffic down there, it is pretty hard. Also, when you are "granny shifting", I think you shift too early causing the engine to run rich so, you are defeating the purpose of trying to save fuel. So, because of that, your mileage doesn't change that much. This is my guess.

Difference in fuel consumption between 100 and 160 km/h? I would say it would be twice as bad, if not more....At high engine speed, a lot of Honda engines, run open loop, thus becoming rich. What does this mean? They use more fuel than is actually required. Why do they do this? So, the catalytic converter doesn't get too hot. When the car is running open loop, the fuel consumption just goes through the roof.....

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04-27-06, 10:34 PM
That would make such a big difference, for me anyways.

04-28-06, 01:59 AM
At least on some cars there's a gallons used function on the DIC. Or a range function, or gallons remaining function. Or all 3 like the Mark VIII.

04-28-06, 09:59 AM
Yup, I loooooove that feature! My deVille has Range, Instant Econ, Avg Econ, and Fuel Used. The fuel used and gas in tank displays are never close to each other. For example, it'll say I have 8 gallons in my tank and I used 8 gallons of gas, I have a 18 gallon tank, so theres two gallons of leeway.

04-28-06, 03:21 PM
I miss that on my FWB. My 91 SDV had it.

But, I never felt it was accurate either. It still fit the pattern of the typical GM non linear gauge. Count the miles between each gallon, it won't add up to linear readings.

04-28-06, 07:29 PM

Are Ford's better?

DopeStar 156
04-29-06, 01:33 AM
My fuel gauge is pretty accurate. Just when it's under half a tank it tends to be easily swayed on wide turns. I just have the traditional "E...|...F" in the center of my dash with a little yellow light when it's low. I always fill from 1/3 of a tank anyway.