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Discussion Starter #1
At the end of March I reviewed the MPG chart that I have kept for my cars since the mid 1980s. I didn’t like the trend I saw.

ECO MT Fuel Economy.JPG

Although my overall combined fuel economy was still slightly over 42 MPG, the 5000 mile running average trend line had dropped over 3 MPG since it peaked at slightly over 45 MPG. This is not a trend I wanted to continue. I decided to start hypermiling my car. The final fill up on this chart was me filling the entire 15.6 gallon tank via a trickle fill to give me the additional range needed to drive to Colorado Springs and back and have sufficient range for my weekly commute. Like most people, my daily commute is an out and back, travelling the same roads in both directions. This eliminates any bias of changing elevations during the commute.

The techniques I settled on were slowing down, pulse & glide, and near zero throttle acceleration from a stop.

Slowing Down

According to Motor Trend, slowing down from 65 MPH to 60 MPH would result in a 4 to 5 MPG gain in fuel economy. I had tested this fuel economy chart at speeds from 45 to 80 MPH and found it accurate at those speeds.

40-MPG-comparison-constant-speed-chart.jpg

On my daily commute this would result in a maximum of 4 minutes added to each direction. This is a maximum only if traffic is actually running at 65 or faster. In congested traffic, I’m not moving at 65 to begin with and there is no impact on commute time. I have a 30 mile one-way commute with 18 miles at a posted 65 MPH and the remainder posted at 45 to 55 MPH. I didn’t slow down the 45-55 MPH sections of my commute.

I had an interesting side effect of slowing down from 65 to 60; the slowest consistent traffic flow is running right about 60 MPH and the faster traffic is running 65 – 75 MPH. Not only did I find a speed to improve my fuel economy but I have reduced my commute related stress by not constantly having to change lanes to pass and then get out of the way after passing.

Pulse & Glide (P&G)


One of the reasons hybrids get such good fuel economy is they have built in pulse and glide. Basically, what this means is that anytime a hybrid coasts it shuts off the gasoline engine and uses its electric motors only. The Cruze can do this as well using Deceleration Fuel Cut-Off (DFCO). The key here is that you must start your coast above 1500 RPM. In order to implement P&G in the Cruze, I had to modify one rules of thumbs about what gear to use. Specifically, the rule of thumb that anyone trying to get the best fuel economy out of their car needs to stay in the highest gear possible isn’t always correct. In order to glide in DFCO, I have discovered that I frequently have to be one gear down from where level ground driving would indicate for best fuel economy. For instance, driving through rolling hills at 45 MPH, the car needs to be in 5[SUP]th[/SUP] gear. Going uphill this means the car will have sufficient torque to maintain speed. Going downhill the engine speed is high enough for the car to enter DFCO, which basically means I get to go up and down hills at just the fuel cost of driving uphill. In 6[SUP]th[/SUP] gear not only will the car be unable to maintain speed while going uphill but the engine speed will be too low to enter DFCO, consuming fuel going both up and down hills. One other place this comes in handy is when approaching a stop sign or red light. Downshift one gear if needed to bring your engine speed above 1500 RPM and then let off the gas. The ECO MT coasts well enough in both 4[SUP]th[/SUP] and 5[SUP]th[/SUP] gear to avoid slowing down too fast.

Near Zero Throttle Acceleration from Stop


This is exactly what it sounds like. My ECO MT idles at 700-900 RPM. I have learned to start the car moving from a complete stop while keeping my engine speed below 1000 RPM. Obviously uphill starts require a little more throttle to avoid stalling on start.

P&G, combined with learning to start my ECO moving without using any throttle, is extremely useful in stop & go traffic. After some practice I have discovered that I can start my car moving while keeping the engine speed below 1100 RPM, and in many cases at the 900 RPM idle, and then delaying shifting until the next higher gear results in 1500 RPM at the end of the shift. This allows the car to go into DFCO anytime I need to let off the gas. DFCO even works in 1[SUP]st[/SUP] gear, but you won’t coast very far before the injectors will turn back on.

Built in Tools


The Cruze ECO has some built in tools to measure the effectiveness of various hypermiling techniques. Using the car’s metric displays, you can show far higher fuel economy numbers. The table below is the conversion for values above 99 MPG.

L/100KM
MPG
Low
High
0.1
2,352.1
1,578.6
4,704.3
0.2
1,176.1
944.6
1,568.1
0.3
784.0
674.0
940.9
0.4
588.0
523.9
672.0
0.5
470.4
428.4
522.7
0.6
392.0
362.4
427.7
0.7
336.0
314.0
361.9
0.8
294.0
277.0
313.6
0.9
261.3
247.9
276.7
1.0
235.2
224.2
247.6
1.1
213.8
204.7
224.0
1.2
196.0
188.3
204.5
1.3
180.9
174.4
188.2
1.4
168.0
162.3
174.2
1.5
156.8
151.8
162.2
1.6
147.0
142.6
151.8
1.7
138.4
134.5
142.6
1.8
130.7
127.2
134.4
1.9
123.8
120.7
127.1
2.0
117.6
114.8
120.6
2.1
112.0
109.5
114.7
2.2
106.9
104.6
109.4
2.3
102.3
100.1
104.5
DFCO is represented by 0.0 L/100KM

Results so far


Tank 1: 49.9 MPG (Pump measured)
Tank 2: 49.6 MPG (Pump measured – snow storm during this tank)
Tank 3: 38.3 MPG (Pump measured – snow storm and service tech idling car for about two hours)
Tank 4: 48.9 MPG (DIC measured – still in progress and improving after a snow storm. First day of this tank was 52+ MPG)

I have driven over 1300 miles since I started this experiment on March 31[SUP]st[/SUP] and even with multiple snow storms dropping several inches of snow each and roughly two hours of idling at the dealership while my HVAC unit was being replaced for the glycol odors, the car is reporting 47.8 average MPG. This past Friday I was able to maintain 60 MPH through the entire 18 mile 65 MPH zone in both directions. I started the day with the DIC reading 47.6 MPG and ended the day at 48.6 MPG, demonstrating the effectiveness of slowing down. I can negotiate bumper to bumper freeway traffic at 45+ MPG, demonstrating the effectiveness of P&G and zero throttle starts.

Final Notes


For a basic tutorial on how to improve your fuel economy, read XtremeRevolution’s thread http://www.cruzetalk.com/forum/27-fuel-economy/5387-how-get-better-fuel-economy.html.

While hypermiling, do NOT make yourself a rolling road hazard. Some extreme hypermilers are very much rolling road hazards and need to be pulled over and ticketed for interfering with the flow of traffic. In my case, it was a smart decision safety wise to slow down from 65 to 60 MPH. This won’t be true for everyone. The P&G techniques will work in any heavy traffic anywhere. I have discovered that most people quickly figure out that although you aren’t accelerating as fast as the traffic in front of you that you end up catching up with that same traffic the next time it slows down. The difference is that you have used roughly half the fuel you would have used to keep up and then slam on your brakes.
 

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Great post! I also hypermile in my Si from time to time. I love the benefits gained from it. You sir however have outdone yourself with the charts. I'd love to see more input from users that also attempt it. My new issue since moving back to the Atl area is that everyone here is pretty much 75% throttle on green lights and you risk getting hit. It was much easier for me back in Ohio to do it.


Sent from AutoGuide.com App
 

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Discussion Starter #3 (Edited)
I remember driving around and in Atlanta - 0 to 75+ and then back to 0 literally as fast as the big SUVs could do it. Repeat as many times as needed to get to your exit. Pulse & glide should still be usable, but not as effective because the full P&G cycle is short.
 

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Discussion Starter #4
I know someone will ask, my spark plugs are gapped at 0.035" per the original spec in the GM Global Connect maintenance guide and I run 91 octane gas. Other than this my engine and engine programming are stock.
 

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Discussion Starter #8
jblackburn is correct - 1200 RPM. I don't have much of a jerk however. The car will also enter DFCO when letting off the gas as high as 5000 RPM.

Entry points for DFCO - 1500 to at least 5000 RPM when you let your foot off the gas while in gear. This is true for all 1.4T Cruzen, manual and automatic. I aim for 1600 RPM to give the car a chance to register the no-throttle condition before it drops below 1500 RPM.

Exit points - 1200 RPM or pressing on the throttle or clutch. The automatics will remain in DFCO while they downshift. The manuals will reenter DFCO within 2 seconds after a downshift is completed and the resulting engine speed is at least 1500 RPM.

I think my ECO MT enters DFCO faster than the 1LT automatic I had for three days while my car was having the HVAC duct box replaced. The 1LT seemed to take about 4 seconds to enter DFCO while my ECO MT will enter DFCO in about 2 seconds. In the automatic, to get the most out of DFCO you need to be in manual mode. Full automatic engages engine braking and thus decelerates significantly faster than manual mode, which decelerates faster than the manual transmission.
 

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Discussion Starter #9
very nice write up. love the charts, they really give you a look at how mpg has gradually increased
Don't you mean "decreased". My current chart shows a real up swing in MPG since the end of the chart I posted. My 5000 mile average has jumped over a full MPG to 42.9 from 41.7. This is just in three tanks.
 

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jblackburn is correct - 1200 RPM. I don't have much of a jerk however. The car will also enter DFCO when letting off the gas as high as 5000 RPM.

Entry points for DFCO - 1500 to at least 5000 RPM when you let your foot off the gas while in gear. This is true for all 1.4T Cruzen, manual and automatic. I aim for 1600 RPM to give the car a chance to register the no-throttle condition before it drops below 1500 RPM.
I use DFCO to slow for all stop stop signs, but downshift to 4th gear to maintain higher RPM to a lower MPH so I am in DFCO a longer period. I actually think this is half the reason I get such good MPG with the automatic.

The 1200RPM when the injectors come back on might be a bit low for the automatic, though I have not tested it. I just use 1500RPM as the point in my mind I want to stay above when in DFCO. That is why I downshift to 4th, 1500RPM is 35MPH in 5th when slowing, so I get at least another 10 seconds of slowdown in 4th while remaining above 1500RPM.

I'll switch to metric and test it out to see the low point DFCO RPM with the automatic sometime in the next few days. You are correct it does take 3-4seconds to enter DFCO with the automatic, knowing this though one just needs to plan ahead.
 

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Discussion Starter #12
The stop & go freeway traffic is what made me decide to try pulse & glide. Since I hate watching my speed drop going uphill I decided one day to simply stay in 5th gear and watch my overall fuel economy driving through Highlands Ranch. I was rather amazed to see, for the first time ever, my average fuel economy go up through that stretch. In the past rolling through in 5th (to go up hill) and shifting to 6th for the downhills I struggled to maintain both speed and average fuel economy. Thus my modification to the rule about staying in the highest gear possible for fuel economy. I actually got started doing near zero throttle starts while teaching my son (Penguin LS's main driver) how to drive a stick shift. I realized the ECU would adjust the throttle for me. It gave him the exact feel for the clutch and friction point in the Lancer he was learning on. Since it takes far more fuel to accelerate from a complete stop than even a very slow rolling motion, I figured why not try and give the car a chance to manage the throttle whenever possible while starting from a complete stop. The ECU in modern cars is an amazing piece of engineering and if you don't fight it can do amazing things for you.

Current tank: 360 miles/49.4 MPG - includes a snow storm on May 1st.
Last 500: 49.6 max average MPG.
Last 1600: 47.6 MPG - don't forget this includes several snow storms and roughly 2 hours of idling at the dealership) When I picked my car up at the dealership the ECO's game display showed right around 25 average MPG for all three ranges of 25, 50, and 500 miles.
 

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Discussion Starter #13
I'd say the changes in my driving style are having an impact. From the car (trip 1) this morning:

Tank Miles: 424.8
Tank Average MPG: 50.2
Tank Average Speed: 40.8

My 500 mile average is at 50.0 and the peak average is also 50.0. I checked in metric and the max (min) is 4.7 L/100 KM, which is 50 MPG.

After the half foot of snow we got last Tuesday & Wednesday the tank average was somewhere between 45 and 46 MPG. I'm on the same tank of gas. This has been almost entirely commuting miles with a couple of in-town errand trips over the weekend.

I'll get a pump measurement this evening as I'm close to a quarter tank which is my "refill" point. The car claims I still have nearly 200 miles left on the tank.
 

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Discussion Starter #14
Filled my tank this afternoon. Since Mar 31 when I started hypermiling:

49.9 MPG
49.6 MPG
38.3 MPG
52.4 MPG

Pump measured average: 47.05 MPG over 1691 miles. This is a 11.4% over my lifetime average MPG.

I have to conclude that not only is the ECO MT one of the easiest cars I've ever hypermiled, but that this car wants to be hypermiled. The hardest part appears to be the stupid artificial tank full fill limit that GM put in to "increase" the EPA City estimate. I suspect that the 38.3 should have been higher than it was because the car reported 49.5 MPG for the next tank. The artificial "full" level makes it difficult to get a consistent full fill-up, which means this car is even more erratic from fill up to fill up than most cars. This simply means that you need to average over more miles and tanks to get an accurate feel for your long term MPG.
 

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The artificial "full" level
The Cruze is so awesome, Chris Christie should be driving one!

I agree on the Cruze wanting to be hypermiled though. I'm getting 38.5 on my tank now, tuned, and with all city driving, and I'm not even trying to hypermile it!
 

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The artificial "full" level makes it difficult to get a consistent full fill-up, which means this car is even more erratic from fill up to fill up than most cars. This simply means that you need to average over more miles and tanks to get an accurate feel for your long term MPG.
The 15.6gallon on the 1LT seems to have about 0.4+/- gallon discrepancy with kick off between pumps, I can imagine the ECO leaving 3gallons of empty space this could be much worse. Since an ECO owner can slow fill to get those extra gallons I imagine the speed of the pump greatly effects how much gas you get.

I have always been a first click(slow) fill person but I would think the ECO would have a more accurate fill up on a fast fill forcing it to kick off and not trickle fill at all.
 

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Discussion Starter #17
The 15.6gallon on the 1LT seems to have about 0.4+/- gallon discrepancy with kick off between pumps, I can imagine the ECO leaving 3gallons of empty space this could be much worse. Since an ECO owner can slow fill to get those extra gallons I imagine the speed of the pump greatly effects how much gas you get.

I have always been a first click(slow) fill person but I would think the ECO would have a more accurate fill up on a fast fill forcing it to kick off and not trickle fill at all.
A slow fill will always get you a more consistent first click off. Turbulence in the tank during the fill process is what causes early click off by creating early "blocks" to the tank vent system and the fill pipe. The pump clicks off when it gets too much splash back from the fill pipe. To reduce tank turbulence, reduce the speed the fuel is entering the tank.

The +/- 0.4 gallon for first click off is about right given the shortness of our fill pipes.

I went back after I posted last night and dug deeper into the 38.3 MPG tank fill up. Turns out this tank included 1.3 gallons of gas after first click off. I usually fill to the first even dollar (no cents) amount after first click off. I went to the third even dollar amount on that tank.

Also, although pleased with 47 MPG, I want more. I have reason to believe I can get my commute to over 50 MPG. My commute is currently 3/4 of my annual driving. The entire reason I went with the ECO MT was for the fuel economy. I got to Grand Junction (250 miles from my home) on 5.5 gallons of gas for just under 46 MPG and this was at the posted speed limits of 65 and 75 MPH.
 

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A slow fill will always get you a more consistent first click off. Turbulence in the tank during the fill process is what causes early click off by creating early "blocks" to the tank vent system and the fill pipe. The pump clicks off when it gets too much splash back from the fill pipe. To reduce tank turbulence, reduce the speed the fuel is entering the tank.
I completely agree in a normal car without 3gallon capacity above fill up kick off, but if one pump is slower than another then you will never get consistent fill up with the Eco. Guarantee the to fast kick off point is more consistent than slow fill with that many extra gallons after kick off to play with.
 

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Discussion Starter #19
I completely agree in a normal car without 3gallon capacity above fill up kick off, but if one pump is slower than another then you will never get consistent fill up with the Eco. Guarantee the to fast kick off point is more consistent than slow fill with that many extra gallons after kick off to play with.
I played with fill speed when I first got my ECO. Slow fill works better. Besides, even on slow fill I can't wash the glass on my car before the pump clicks off - the tank is too small.
 
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