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I posted once here in an introduction thread and now that I picked my new vehicle I'm back. I bought a 2002 Chevy Cavalier 2.2L 5spd from Ebay for $3299 and have been using it to deliver pizza and just get myself around. It's rated 24/34 city/hwy. I was able to pull 42mpg from the automatic version (which I still own) so I was optimistic about what I could do with the 5spd. It's a good car and I like it. The only problem was that Chevy decided that it should idle at 900 rpm (0.4gph) and cruise in neutral at 1200 rpm (0.6gph) which was a huge waste of fuel. My auto with the same engine only idles at 600rpm. I suppose this is a driving aid to keep inexperienced drivers from stalling it.

The 57.1mpg I got was on a 12 mile circuit around my area. First, I took off the vacuum hose from the brake booster and blocked most of it with my thumb. The car's computer adjusted the idle air control valve to compensate and at that point, I unplugged the valve and put the hose back. The car's idle dropped to 490 rpm and shook a bit, but now only used 0.2gph when my foot was off the throttle. I also added an engine kill switch so that I could pulse and glide. I didn't want to wear out the starter so when I coasted to a red light or stop sign, I let out the clutch in 5th to get the engine going again. On continuous highway driving at 55mph, my car gets 43mpg, probably due to aerodynamic drag. If only I could eliminate the stop light idling, I think I could break into the 60's. Even if I don't, it's not too bad for a $3299 car with no batteries.

Hi Specter:

___How did you measure the FE over the 12 mile segment and what was your total tank including the short segment? My last tank was similar with a lot of work but I only needed to use NICE-On maybe 15% of the time and only when the 12V fell below 11.9 static under a FAS.

___Good Luck

___Wayne

First of all, welcome to CleanMPG!

Those were impressive stats!

Ever since returning from HybridFest, I've been doing FAS approaching stops a lot more. It really saves a lot of fuel. Granted, not charging to a stop saves, having fuel-cut off and autostop helps more, but FAS takes it to a higher level.

specter - excellent work!

The 57.1mpg I got was on a 12 mile circuit around my area. The car's idle dropped to 490 rpm and shook a bit, but now only used 0.2gph when my foot was off the throttle. On continuous highway driving at 55mph, my car gets 43mpg, probably due to aerodynamic drag. I



Um, ok...What do you have, a little gadget that shows instantaneous mpg based on inertia? How did you get a fuel flow rate? Not very scientific, and not very accurate, but I guess it gives the driver a good feeling if nothing else. 43mpg continuous IS impressive. What do you attribute this high mpg to?

The BEST way to measure mpg is over many tanks of fuel. Measure your actual miles (and don't assume your odometer is correct, because chances are it's not) divided by actual gallons of gas put in your tank. Do this for about 10 tanks, always refilling the tank to the same level. Then come back and tell us what you're getting for mpg.


If you want to figure out an odometer reading factor, use the highway markers. Start at any mile marker (mm), say mm 97 for an example, and note your odometer and trip meter reading. Drive many miles, a good 100 miles is a good distance. So, you should be at mm 197, right? Now, how many miles does your odometer (trip meter)say you went? Let's say it reads 103.4 miles. What you do next, is divide 100 by 103.4 which gives you .967118. This is your mileage correction factor, and whenever you drive a full tank of gas and fill up, I assume you reset your trip meter. Take you trip meter reading and multiply it by .967118. This will give you a true mpg, and something we can all compare our mpg to. ;)

Andy

That was not exactly the best way to make an intro :( ....hope the next post is more positive with a little info about your car, etc...

Spectre, it's still relatively speaking the best run you have had

I tend not to realy care if somones mpg is off by a few percent. Most people are competing with themselves and not others.

No need to get all scientific about getting it as accurate as possible. The idea is to just do better each time.

Andy,

I don't know for sure, but I would bet that Specter is using a ScanGauge for his MPG information. That's what most of us use if we don't have a fuel consumption display (FCD) in our vehicles from the factory. It is very accurate once dialed in, a procedure that does involve comparing the ScanGauge's reading to miles/gallons calculations over the course of a few tanks.

Good point about the odometer, though. Something else that has been suggested is to use Google Earth route measuremets to calibrate the odometer. A "measured mile" is quite valuable but may be hard to find in some locations. The rest of the mile stakes tend to be mile-ish stakes, though I suppose they probably work just fine over a longer distance. Either way, good suggestion.

And welcome to CleanMPG! Care to post in the Intro section if you haven't done so already? Sounds like you have some experience keeping accurate records of your own fuel economy. There's loads of information on these pages. Odds are you will find as many others (myself included) that what we once thought was "the right way" tends to leave quite a bit of room for improvement. An open mind will prove to be a great asset ;)

Hey, I'm not trying to stir up the pot, but making claims of 57 mpg over a 12 mile circuit is bogus. Is this a feel good site or a scientific site? Looking down at a box that says your currently getting 57 mpg, or that last run was 57 mpg, is feel good.


How would you like it if I posted a number like 57 mpg, only to find out my odometer is off by 10%? What good is it if there is NO standard? Information on how to get better gas mileage is a good thing. How would you like it if I bought one of those things and did a run down a mountain, and posted my mpg? Wouldn't you be impressed with my high mpg? Gas mileage varies SO wildly while driving, it is not useful information, other than to the driver to know at that moment what his right foot is doing. You're talking miles per gallon, and 12 miles won't even come close to 1 gallon in his car. Is that useful information to us?

Information like: I have averaged 25 mpg over the last 10 tankfuls with a high of 29 and a low of 22. After incorporating this ONE change into my driving technique, AND another 10 tankfuls of gas, my mileage over those last 10 tanks was 31 mpg with a high of 33 and a low of 25. I can assume that my change in technique has accounted for a 6 mpg average increase.




I think this is a great site, and it has a lot of information. A few people have gone to the trouble of putting together a glossary for acronyms, etc. It would be nice to see standards on posting mpg, ie. minimum miles driven for that claim. Do you see my point?

Hey, I'm not trying to stir up the pot, but...

I'm glad you agreed to make your next post an intro so you won't be a stranger....people meeting face-to-face get acquainted before quibbiling - better chance of getting somewhere and more diplomatic.

As Tom said, our goal at CleanMPG is for self-improvement, so they don't require the precision you are suggesting. I might understand such exact measurements at the Tour de Sol or some other competive event.

I would be interested in knowing more about diesels like your TDI - assuming it's a diesel.

Hey, I'm not trying to stir up the pot, but making claims of 57 mpg over a 12 mile circuit is bogus. Is this a feel good site or a scientific site? Looking down at a box that says your currently getting 57 mpg, or that last run was 57 mpg, is feel good.

For some of us 57 mpg over 12 miles is not bogus. After a while you will start to believe these numbers when you start to see how much you can improve. Even if he is off by alot, if he is comparing 57 to what he gets next than thats all that matters. This site isn't about to get scientific data. It is about improving your mileage in whatever you drive. If your meter says 57 today and it says 59 tomorrow then we have done our job.

In theory you can get infinite mpg over 12 miles if that 12 miles is downhill and your engine isn't running. So don't dismiss something as bogus because you realy don't know. This site isn't a "feelgood" site, but we do encourage people to do better. If that makes them feel good then fine. Whats wrong with that. But again, don't go calling shenanigans because ultimately on this site it isn't how high you can go, but how are you doing today vs yesterday.


How would you like it if I posted a number like 57 mpg, only to find out my odometer is off by 10%? What good is it if there is NO standard? Information on how to get better gas mileage is a good thing. How would you like it if I bought one of those things and did a run down a mountain, and posted my mpg? Wouldn't you be impressed with my high mpg?


It wouldn't phase me at all because your 57mpg being off by 10% doesn't mean anything to my mileage. We don't need a standard because we aren't judging winners and losers on this site. Sure, there are some merits and acolades when someone does well, but I think you will notice they are individual accolades and not that someone beat someone else


Gas mileage varies SO wildly while driving, it is not useful information, other than to the driver to know at that moment what his right foot is doing. You're talking miles per gallon, and 12 miles won't even come close to 1 gallon in his car. Is that useful information to us?


This is why we generally talk about tank mileage. If we have a good segment we might come here and let everyone know, but that is just so we are encouraged to keep it up or to talk about any techniques we migh thave learned.


Information like: I have averaged 25 mpg over the last 10 tankfuls with a high of 29 and a low of 22. After incorporating this ONE change into my driving technique, AND another 10 tankfuls of gas, my mileage over those last 10 tanks was 31 mpg with a high of 33 and a low of 25. I can assume that my change in technique has accounted for a 6 mpg average increase.


We have the database (crude though it is) so we can track each tank and see trends and make notes of events in that tank and techniques used. Hopefuly the database will grow get get better and maybe even more scientific in the future. But for now you can do simple trending and note taking with it. I hope you find it useful.

I think this is a great site, and it has a lot of information. A few people have gone to the trouble of putting together a glossary for acronyms, etc. It would be nice to see standards on posting mpg, ie. minimum miles driven for that claim. Do you see my point?

I see your point. But given that there are so many variables that could make your reported mpg off by a bit it realy is difficult in the real world to get scientificaly valid data. The best we can do is try to get consistant data.

BTW, welcome to the site! And dont' worry so much about others MPGs. Make increasing your own MPG your challenge. And don't worry, if it is 60 or 20 we won't judge, we just want to help each other do better.

Hi Andy:

___Specter is probably using a Scan Gauge I and if it’s calibrated, he is darn near dead on either through its iFCD, daily segment aFCD, and overall Tank FE. Please pull back a touch and speak like you were talking to a new friend. Once you have used a Scan Gauge or have driven an automobile with a built in i and aFCD, you will wonder what you have been missing. Guessing FE data over a short segment via the fuel gauge without something like a Scan Gauge is a lesson in futility. There is really nothing better then pics to show what is available from SG-II …

http://www.cleanmpg.com/photos/data/523/SG-II_Accord_65_4_mpg_Segment_JPG.jpg
Fuel Economy over today’s Segment

http://www.cleanmpg.com/photos/data/523/SG-II_Todays_Segment_Distance.jpg
Distance of today’s Segment

___Not only can you see your iFC in real time, you have a multitude of parameters viewable in real time or as MAX through a given segment's drive.

___Specter, indeed a nice segment and I hope you have a cal’ed Scan Gauge as there really is nothing else like it … Besides Yoshi’s SuperMid that is ;)

___Good Luck

___Wayne

I see someone removed my 2nd post, but Tbaleno was kind enough to quote it. I guess I'm not completely in-tune with the intentions of this site. Sorry for stirring it up.

___Specter, indeed a nice segment and I hope you have a cal’ed Scan Gauge as there really is nothing else like it … Besides Yoshi’s SuperMid that is ;)


___Wayne

A cal'ed Scanguage2 is not an easy task but once it is, it's priceless. I've had my SG2 for about a month or so and I think I finally got it dialed in. The last time I topped off the gas pump, which by the way was inspected earlier this month, showed 4.721 gallons; SG2 reported 4.7 gallons. Calculated mpg was 44.9 and SG2 showed 45.6 which, if I calculated right, is around 1.5% off. I think for now I can pretty much rely on SG2 numbers for now. Getting back to the above quote, I think a properly cal'ed SG is the single most important piece of FE equipment.

Hi Andy:

___I am the one who pulled it but it is only hidden, not deleted … I wanted Tom to take notice of the whole thing first because from your second post, it sounded as if you did not know what a SG-I or SG-II was or what it can do for you. If Specter has a calibrated one in his Cavalier, he is within 1 - 2 mpg’s of actual and you can take that to the bank.

___DiamondLarry, you are dead on about how valuable SG’s can be. I don’t know how I could have lived so long without one myself! While at HF2006, I borrowed one from Eric so Dan could take the FE Challenge run in his Prius II with something that could read above the Prius’ self imposed 99.9 mpg limit. We could not cal it over ¼ or a whole tank of course but cal’ed per the Prius II’s instrumentation and found it to be ~ 4% under reporting over a 2 and then again over a 4 mile segment. He nailed a 115.x mpg FE challenge run with the SG showing 111 by the way! Another Internet friend from Canada (Kip Munro – known as B1shmu63 over at IC) arrived later on Saturday afternoon. His Insight had thrown a CEL about 100 miles prior to arrival. We pulled the code (Insight’s famous O2 again :(), recorded it, then removed it … Not only are the various i and aFCD displays incalculably valuable (I am improving the Accord’s highway FE by the day because of its real world feedback far beyond the Accord’s extremely limited 50 mpg max iFCD in the NAVI’s TC), just knowing when a thermostat is about to go by watching something as simple as the Coolant temp is to me a godsend … Another item you may find interesting. The SG-II in the Accord using just the ICE setup was 1.1% under reporting from actual over her last 1,083 mile tank! The SG-II is extremely accurate right out of the box considering that small a variance from actual over that kind of distance while throwing everything but the kitchen sink at her …

___Good Luck

___Wayne

I have also found that the timing doesn't go to it's farthest advance until the coolant temp reaches 145-150F by watching the SG. On my Saturn the timing won't advance past 30degrees until the coolant reaches that level, at which point it will go as high 39 degrees. I think I'm only beginning to find all of the benefits of having an SG.

Hey, I'm not trying to stir up the pot, but making claims of 57 MPG over a 12 mile circuit is bogus. Is this a feel good site or a scientific site? Looking down at a box that says your currently getting 57 MPG , or that last run was 57 MPG , is feel good.

I warmed up the engine in the driveway, clicked reset on my ScanGaugeII, drove the circuit, pulled back in the driveway, shut off the engine and took the CURRENT reading which is not instantaneous.

How would you like it if I posted a number like 57 MPG , only to find out my odometer is off by 10%? What good is it if there is NO standard?

My speedometer and the speed the SGII reads is within 1% of my GPS, which is accurate to the tenth of a mph. Also, the SGII's fuel rate has been calibrated over the last ten tanks.

Information on how to get better gas mileage is a good thing. How would you like it if I bought one of those things and did a run down a mountain, and posted my MPG ? Wouldn't you be impressed with my high MPG ?

That is why I drove a CIRCUIT. There are no elevation differentials in a circuit because the start and stop points are at the exact same elevation. For every hill I coast down, there's one to climb.

Gas mileage varies SO wildly while driving, it is not useful information, other than to the driver to know at that moment what his right foot is doing. You're talking miles per gallon, and 12 miles won't even come close to 1 gallon in his car. Is that useful information to us?

You're right, it didn't come close to a gallon, but that's irrelevent because my SGII's CURRENT (not instantaneous) reading is what I posted here at the end of the circuit.


By the way, I did post an introduction a while back: http://www.cleanmpg.com/forums/showthread.php?t=1242

Here's more info on my car...
2002 Chevrolet Cavalier Coupe 2.2L 5spd
Tires @44 psi
Synthetic 5W30
90K mi
115HP
Idle fuel rate/rpm: 0.4gph/900 (trying to lower to 0.25/550)
Factory intake and exhaust systems
~40lbs aftermarket stereo equipment
High output alternator
High capacity battery

43mpg continuous IS impressive. What do you attribute this high MPG to?

Mostly to driving 55mph in a well maintained 2.2L with well inflated tires, good aerodynamics and gearing. I also have a 1998 automatic Cavalier that gets 42mpg highway so I don't think this is a factory freak. At 65mph, the car will get close to its EPA rating, but at 55mph (2000 rpm) it does quite a bit more.

specter,

I don't think you need to defend yourself - we trust you had a great ride. :)

Hi Specter:

___As Chuck just said, great job and everyone here knows how much work it took to get there ;)

___Good Luck and don’t give up!

___Wayne