Gas mileage mystery

He wrote: "Itseems that I get about 140 iles to the first half tank...the second half drains...I only get about 80 miles from the middle point of the gage to E..."

That is equivalent to mpg only if you assume that each half of the gauge represents the same number of gallons.

Reply to
Marvin
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He also wrote "If I fill up a half empty tank, I'm getting close (not quite)

20 mpg...if I let it get near Empty I'm looking at about 14 mpg". That is (possibly) incorrect only if you assume it was based on the gauge. You think he didn't even twig that "near empty" could mean another 50 miles?
Reply to
jg

what really surprises me is that Volvo never included a LOW LEVEL warning light...

my 70's Fiat had that, my '86 Corolla had that... but my 760 doesn't!! My

760 ('87) also doesn't have tilt steering, while my Alfa Romeo of the same era had tilt/telescope!! What's up with that?!?!
Reply to
M.R.S.

Of course Volvos have a low fuel contents light. It is part of the fuel gauge and is a small Red or Orange dot that lights up when there are about 6 Litres of fuel left in the tank. Your 760 is just before the facelift model which does have the steering wheel tilt as do subsequent 760s and

960/S90/V90s. The tilt lever is to the left of the wheel (UK) between the casing and the dash knee roll. Might be to the right on USA/Canada models.

All the best, Peter.

700/900/90 Register Keeper, Volvo Owners Club (UK).
Reply to
Peter K L Milnes

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People are often surprised when they discover what has been traded for economy, convenience, sales attractiveness or someone's idea of progress. Just think if it was a Ford device you'd probably be better off without it.

Reply to
jg

If I could read minds, I'd know. My impression from reading between the lines of his question is that he assumed that his gas guage accurately reflects the volume of gas in the tank. My training as a scientist is not to trust any measuring device until I've calibrated it, unless it came from a source I knew did a good calibration.

Sometimes, the exactness of the reading isn't vital. I know my bathroom scale is off from the scale in my doctor's office. But I use my bathroom scale mostly to tell me whether I'm gaining or losing weight, so it only needs to be consistent, not highly accurate.

Reply to
Marvin

If you wen't back as far as I do, you would remember when the dashboard had a meter that showed how much current was going out of or into the battery. Voltage regulators weren't so good, and we worried about overcharging the battery. But we didn't have an outside temperature reading.

Reply to
Marvin

Most people never bother to do the math... If you commute 30 miles and it takes an hour (not uncommon in LA traffic), you're averaging 30 miles per hour. Why then, is it necessary to go 70 mph, zero mph, then 70 again for a few minutes? Or, go 50 mph between signals, only to sit at the next red light? I only commute 10 miles. It takes between 20-25 minutes. I roll along at

30-35 mph while others go flying by at 45-50, only to sit at the next signal. Surprise, surprise, the light goes green just as I roll up to it and I never moved my foot on the gas or touched the gas wasters (brakes.)
Reply to
Clay

...and if you didn't flash the field on the generator when you changed the battery, it wouldn't charge at all.

Reply to
Clay

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...can't read minds but can read between lines :) Sorry to be argumentive, when I arrived at the same conclusion as Marvin (measured properly) people assumed the fuel gauge was to blame. A lesson in how quick many are to assume one is stupid, I give more credit for intelligence as a direct result.

Reply to
jg

hehe... well, I think a safe thing would be a low level light, prevents you from getting stranded on the highway.

Another poster suggested it comes on at 6litres... I've never been that low, but that is QUITE low, the gauge dips way into the red and I start to sweat there.. the light has never come on since the car was new.(where is it? it's not a separate indicator which is obvious, unless it is backlit in the red section, which I doubt... I can take a pic).

Oh, and Fiat 500s didn't have a fuel gauge, JUST a light ;)..

Reply to
M.R.S.

Every fuel gauge I've had a chance to check for lineraity failed the test. Others report the same experience. It is a reasonable and likely explanation of the original poster's observation.

Reply to
Marvin

You only have to look at the arrangement to know it won't be very accurate, it's an equally big assumption the inaccurate gauge was used to arrive at firm mpg numbers. Since I have repeatedly varified the same behaviour in another car, measured by the pump, for me the obvious explanation is much less likely. Rather than dismiss it based on assumption, I am interested in why it happens at least in some cars, because I know it does happen.

Reply to
jg

Well...I have done the first two fill-up calculations....and there is nothing that dispels my belief that I get better mileage early in the tank.

I filled up at a half tank...I got 163 miles on 9.18 gallons of gas I then filled up at around 3/4 tank....the gage only has a hash mark at the half tank and the red line at about an 1/8 tank... the 1/4 tank was actually 5.25 gallons and I got 104 miles on that 5 gallons.

So, those who said the gage is not calibrated to precision are correct, but I still seem to get better mileage with more fuel in the tank...go figure.

Mike

Reply to
ChampaignTurbo

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