Miles Per Gallon = Amazing

[klipper]

Hello-

I did a very informal test on my Red Line today driving into work. Using the fancy "instant MPG" meter (which I realize isn't ENTIRELY accurate) I took down some observations.

@ 55 MPH = 49 MPG

@ 65 MPH = 44 MPG

@ 75 MPH = 36 MPG

Test Case:

Use the pedal to get the car to speed. Engage Cruise Control at designates speed. Wait 1 minute for the MPG to stabilize out. Repeat process coming the other way on the freeway. Average and round the 2 numbers. I was using the stretch of I - 15 in Utah from Centre street to University Ave. in Provo for my test case (as it is pretty flat)

I realize these aren't perfectly accurate numbers, but I was still BLOWN away with the results. Everyone else see similar results?

[RedSkyWV]

I tried the same idea in WV using our VERY short stretches of flat/straight interstate.
I used 70-60-50 and got 29, 32.5 (fluctuated 32-33) and 38mpg respectively.
Your numbers seem extremely high, but I hope they're accurate as that's great

[klipper]

I am very skeptical myself....I'll bust out my camera and video it so I can make sure I'm just not changing them in my mind

Sadly, she's going into the dealer today to get her Leather / Paint / Dash treatment...No R/L for me for 2 days

[RedSkyWV]

How long of a straight stretch are you running? I'd say I was going about a half mile, maybe just under, which is a HUGE straight area for here

[klipper]

Just a hair under a mile. I need to take it down towards Las Vegas where I can get a good solid 10 miles a run or so...

[mikecronis]

I find "Instant MPG" is a bit of a joke. The DIC's "Average MPG" is far more accurate. I'm getting 31.2 MPG over the last 3 tanks. DIC says 31.5 MPG. Pretty close!

[GO_DRVN]

Out at the NASSM in Las Vegas I got closer to 99.9 for a pretty good stretch leaving the cabin where we had lunch on Sunday. Could have been the downhill, clutch in and at idle for like 6 miles. But it was fun while it lasted.

Pulling in the other direction going to lunch was a much different number.

Under load and on the hills these engines don't do nearly as well as on a flat road with no wind. However, the average of all of the miles I have driven show that mine does better than the EPA estimate, especially when I don't stomp the pedal all the time.

[ceeker]

Remembers Stephen's comment:

"Gas Tank Reading #%%$: All I can say is probably the usual spiel that you get from Saturn. I had to test drive with a customer for 45 minutes once. He said his MPG's never got over 22 in his Aura...I told him "I bet I can make it say 30" I won the bet by getting it up to 31.4 MPG's. This is directly related to your gas gauge question.

The gauge on the dash gets it's info from the logic on the cluster...the cluster logic gets it's info from the PCM/EBCM. The info it's mainly tracking is RPM's, accelerator pedal position, and throttle position (and obviously the fuel level sensor). I've been told by the engineers that there is an equation that calculates the fluctuation of your fuel gauge based on the before mentioned inputs.

If you top off your tank...then floor it for 2 minutes on the highway...your fuel gauge will drop about 1/4 to 1/8 of a tank. You didn't lose a 1/4 tank...but the computer is telling you that will if you keep this sustained speed. When you slow down...magic...your fuel tank will fill itself and the gauge will rise. I've seen it, I've demonstrated it for customers, and they have literally told me they glad to see how it works.

I don't have an actual MPH that is optimum for all the computers in your car, but 55 to 60 seems to be about right. Any acceleration or deceleration deviation from that will send the fuel gauge moving in the +/- range more quickly."

I believe the instant MPG reading is based on your driving style since you last started your car!

[lostcause]

Originally Posted by ceeker

Remembers Stephen's comment:



If you top off your tank...then floor it for 2 minutes on the highway...your fuel gauge will drop about 1/4 to 1/8 of a tank. You didn't lose a 1/4 tank...but the computer is telling you that will if you keep this sustained speed. When you slow down...magic...your fuel tank will fill itself and the gauge will rise. I've seen it, I've demonstrated it for customers, and they have literally told me they glad to see how it works.

I don't have an actual MPH that is optimum for all the computers in your car, but 55 to 60 seems to be about right. Any acceleration or deceleration deviation from that will send the fuel gauge moving in the +/- range more quickly."

I have personally experienced something similar. Just took a long roadtrip to the tail of the dragon. On long highway stretches I would average between 30 and 33 mpg or so. As the gas gauge got lower, say it got to where it showed about 1/4 tank, estimated miles remaining would show something like 100 or so with 1/4 tank. This was after extended driving at at a consistent 70 mph or so with no stops or accelerations.

Then I'd pull off the highway and within minutes, the estimated remaining miles would drop to like 30 or so and the gas gauge would dramatically drop to less than 1/8th and sometimes the low fuel indicator light would even come on when not more than a minute or two ago it had shown 1/4 tank.

[anon]

Throw in a Scangauge II, and you will get accurate real-time AND trip/tank mpg readings.

[Bogie]

Personally, I think tying the GAUGE to fuel rate was a DESIGN mistake. The gauge should show HOW MUCH fuel is in the tank. If I have half a tank, it should read half a tank.

I understand what the designers were trying to accomplish, but they failed to realize a very important concept in human processing. Humans already know how to integrate (in the Calculus definition) a gauge.

[Aside: I'm getting technical, but even if you only finished the 3rd grade, believe it or not, you can do differential and integral calculus...humans do it all the time and don't even know it. We go to four years of college to learn how to express it and communicate it, but we already know how to do it....whether you realize it or not].

Differential calculus is the ability to understand and compute rates of change in something. How fast am I driving? Or, how fast is the fuel gauge changing?

Integral calculus is sort of an undo of differential calculus (or a summation of the differential effects). "If I'm doing 60 mph, I will go 60 miles in one hour...120 miles in two hours, etc.". Or, in terms of the gauge, if it falls a quarter of a tank in thirty minutes I know I've burnt a quarter of my fuel in thirty minutes. I've got two hours of fuel.

Of course, if you drive easier or harder, the gauge will change accordingly. But here's the kicker. We humans CAN DO THE MATH without even thinking about it. We automatically integrate the gauge to figure out what we have left or how far we can go.

By electronically integrating the gauge, the designers have screwed with our own internal subconscious integration algorithm. This causes far more confusion than it solves. All I want to know, with a GAUGE, is how much fuel is left in the tank. Not some virtual quantity based on my most recent driving habits. DESIGN mistake...for a GAUGE!

Now, the DIC. No problem. If you want to show me miles left....or whatever with a number....no problem. But don't do it with a GAUGE. Bad design. Stop it. Too much electronic wizardry...not needed.

[TulsaSky]

I have 1/2 tank of gas in the sky, I remember that it is a 16 gal tank, sounds about right so that is 8 gal of gas or approximately 200 miles since I get average 27 miles to gallon on the DIC, so I agree that miles left to my tank of gas on the DIC is useless, I never use it. Maybe if I was heading across the desert and the last sign before the last station said 350 miles and I only had 3/4 of a tank, heck just pull in and top off the gas why even look at the DIC gage easier just to fill it up and hope for the best crossing the desert. I for one keep the gas tank or fill the cars up once I get to a 1/4 tank of gas why chance running out of gas, besides the get a way car needs to gassed up and ready to go!
Now my spouse likes to take chances live on the edge drives his pickup till the orange idiot light comes on saying LOW FUEL, he pulled that stunt on the trip to Florida once in the impala, gas is cheaper in Georgia so were not stopping for gas till we cross the state line. As we pulled into the station the idiot light came on, low fuel told him I would make the call to his Mom and explain why we were late sitting out in the middle of nowhere waiting for OnStar to show up with gas because he wanted to save 3 cents a gallon on gas, darn if we made it

TulsaSky

[Lil GTO]

Originally Posted by Bogie

Personally, I think tying the GAUGE to fuel rate was a DESIGN mistake. The gauge should show HOW MUCH fuel is in the tank. If I have half a tank, it should read half a tank.

I understand what the designers were trying to accomplish, but they failed to realize a very important concept in human processing. Humans already know how to integrate (in the Calculus definition) a gauge.

[Aside: I'm getting technical, but even if you only finished the 3rd grade, believe it or not, you can do differential and integral calculus...humans do it all the time and don't even know it. We go to four years of college to learn how to express it and communicate it, but we already know how to do it....whether you realize it or not].

Differential calculus is the ability to understand and compute rates of change in something. How fast am I driving? Or, how fast is the fuel gauge changing?

Integral calculus is sort of an undo of differential calculus (or a summation of the differential effects). "If I'm doing 60 mph, I will go 60 miles in one hour...120 miles in two hours, etc.". Or, in terms of the gauge, if it falls a quarter of a tank in thirty minutes I know I've burnt a quarter of my fuel in thirty minutes. I've got two hours of fuel.

Of course, if you drive easier or harder, the gauge will change accordingly. But here's the kicker. We humans CAN DO THE MATH without even thinking about it. We automatically integrate the gauge to figure out what we have left or how far we can go.

By electronically integrating the gauge, the designers have screwed with our own internal subconscious integration algorithm. This causes far more confusion than it solves. All I want to know, with a GAUGE, is how much fuel is left in the tank. Not some virtual quantity based on my most recent driving habits. DESIGN mistake...for a GAUGE!

Now, the DIC. No problem. If you want to show me miles left....or whatever with a number....no problem. But don't do it with a GAUGE. Bad design. Stop it. Too much electronic wizardry...not needed.

I think a better example of this unconscious integration may be how we adjust our speed to merge with traffic or to avoid (well mostly) accidents. We are constantly calculating how much we need to speed up or slow down just to get from point A to point B - largely without the need for any gauges in our own vehicle and certainly without any gauge that tells us the speed (vector) of the other traffic.

Which is not to say that the level of precision we achieve is anywhere near what is mathematically possible - but for real world situations - in front of the truck rather than under it is sufficient.

[uranium-238]

...and to think my calc teacher told me i couldn't do cal in my head and still get a good answer...

to bad a fix for the gas gauge isn't as simple as slapping a differentiating circuit on the guage.

[Bogie]

Originally Posted by TulsaSky

I remember that it is a 16 gal tank

You might want to review the specs.

[TulsaSky]

Originally Posted by Bogie

You might want to review the specs.

Lets see the Corvette has 2 9-gal saddle bag tanks, 18 gallons, my Alpine has 2 5-gallon saddle bag tanks 10 gallons of fuel, not sure what the big Impala has closer to 20 gallons I think, and not sure what the Sky is but it is more then the Alpine less then the Corvette, so bogie what is it?

TulsaSky


OK had to look it up its on the specs for the car on-line, 13 gallons! no wonder I seem to be stopping for gas all the time!
Calculator in hand so if I get on average 27 mpg then the most I get out of a tank of gas in 351 miles, now I know!
Guess if I had to cross the desert and it's 400 miles I better take some gasoline with me, I won't make it!

[klipper]

Where ya gonna store it? The trunk? :P

[skycoop]

I just made a trip from Louisville to Atlanta and back and averaged 34 mpg... excellent considering my high speed and the treck through the mountains.

[SKYLORD]

Originally Posted by Bogie

Personally, I think tying the GAUGE to fuel rate was a DESIGN mistake. The gauge should show HOW MUCH fuel is in the tank. If I have half a tank, it should read half a tank.

I understand what the designers were trying to accomplish, but they failed to realize a very important concept in human processing. Humans already know how to integrate (in the Calculus definition) a gauge.

i agree. and now when you pull off the highway reading half full but in reality you have less you feel ripped off when you fill up. cuz now you're buying more than can fit in the tank if you had a half full tank.

[mikecronis]

13.3 gallons.

[GaryH]

Originally Posted by mikecronis

13.3 gallons.

Page 333 of my owner manual says 13.6 gal. I don't know about all the guages/DIC/etc. All I know is miles driven divided by gallons used = miles per gallon. Just simple math for my simple mind.