At the end of March I reviewed the MPG chart that I have kept for my cars since the mid 1980s. I didnt like the trend I saw.
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.
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, Im 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 didnt 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 isnt 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 5th 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 6th 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 4th and 5th 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 1st gear, but you wont 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 cars metric displays, you can show far higher fuel economy numbers. The table below is the conversion for values above 99 MPG.
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 31st 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 XtremeRevolutions thread http://www.cruzetalk.com/forum/27-fu...l-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 wont 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 arent 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.
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.
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, Im 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 didnt 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 isnt 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 5th 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 6th 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 4th and 5th 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 1st gear, but you wont 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 cars 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 |
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 31st 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 XtremeRevolutions thread http://www.cruzetalk.com/forum/27-fu...l-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 wont 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 arent 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.