How to Drive a CMAX Hybrid/FFH to get Great Gas Mileage

[Billyk24]

This is a little "off-target" for this thread but want to provide some information.   My RAV4 hybrid that has three motor generators (the third powers the rear wheels only) like the up coming Lincoln Corsair PHEV.   In a nine mile drive home that featured a 0.7 mile downhill, I got 64.7 mpg and the state of charge increased to 77% at the bottom of the downhill.   I had a 13% increase in the state of charge on the downhill run which is double what my CMax Energi does.   That third MG significantly increases your SOC compared to the standard two (MG1-MG2).    I was not trying to use all the "hypermiling tricks" for this drive and did not use the EV only set button on the vehicle as I drove as I normally would with normal to light traffic.      I's sure many of you could have "beaten" the 64.7 mpg figure.  Those of you considering a newer vehicle may want to look at those that have a third MG setup.   

[ptjones]

I have been thinking about what strategy I will use to improve My 2020 FEH Plugin gas mileage on Hwy trips, when I finally get it. I looked at Energi Posts and it seemed like they drive them like Hybrids and only drive EV at slower speeds .  I have an Idea to improve MPG's using HVB EV to control ICE WT.  Here are the important info for improving MPG's for an Energi:

 

1. ICE runs too cold for maximum efficiency, I found running between 215 to 226*F WT is the best temp range and you need to use Grill Covers to get that high.

2. You gain about 4 mpg using Grill Covers, 2 mpg for reduced Drag and 2 mpg for improving ICE efficiency with higher WT's.

3. Most of the time the ICE WT will be just fine with Grill Covers on, but with significant uphill climb ICE WT will go up, at 225*F I would go to EV Mode for a minute allowing the ICE to cool down.  With my Hybrid I use heater/defrost to lower WT which is a waist of energy.

4. BYW using Neutral to coast down hill improves MPG's and cools the HVB and ICE down.

5. I would guess that a 4 to 5 mpg improvement could be realized doing this.

 

Let me know what you think.  

 

Paul

[plus 3 golfer]

On 5/3/2020 at 12:39 PM, ptjones said:

I have been thinking about what strategy I will use to improve My 2020 FEH Plugin gas mileage on Hwy trips, when I finally get it. I looked at Energi Posts and it seemed like they drive them like Hybrids and only drive EV at slower speeds .  I have an Idea to improve MPG's using HVB EV to control ICE WT.  Here are the important info for improving MPG's for an Energi:

 

1. ICE runs too cold for maximum efficiency, I found running between 215 to 226*F WT is the best temp range and you need to use Grill Covers to get that high.

2. You gain about 4 mpg using Grill Covers, 2 mpg for reduced Drag and 2 mpg for improving ICE efficiency with higher WT's.

3. Most of the time the ICE WT will be just fine with Grill Covers on, but with significant uphill climb ICE WT will go up, at 225*F I would go to EV Mode for a minute allowing the ICE to cool down.  With my Hybrid I use heater/defrost to lower WT which is a waist of energy.

4. BYW using Neutral to coast down hill improves MPG's and cools the HVB and ICE down.

5. I would guess that a 4 to 5 mpg improvement could be realized doing this.

 

Let me know what you think.  

 

Paul

Point3 - EV energy is not free and more expensive when charging HVB while driving than from wall (maybe not at $1.50 per gallon and no cheap EV / off peak electric rates).  If you can stand the additional cabin heat, that’s likely the best way (other than slowing down going up the hills).  
 

It seems intuitive that EV is best used anytime ICE would be operated at low torque demand which generally is when cruising at lower speeds, at moderate speeds on level and slight downgrades, and at higher speeds on steeper downgrades.  This is basically like a hybrid operates until charge depletion requires ICE to come on at higher torque to charge HVB and to propel the car.  So, between plug ins, one would want to use EV wall charge on stretches of the road best suited for its efficient use which I doubt is going uphills.

Edited May 5, 2020 by Plus 3 Golfer

[ptjones]

26 minutes ago, Plus 3 Golfer said:

Point3 - EV energy is not free and more expensive when charging HVB while driving than from wall (maybe not at $1.50 per gallon and no cheap EV / off peak electric rates).  If you can stand the additional cabin heat, that’s likely the best way (other than slowing down going up the hills).  
 

It seems intuitive that EV is best used anytime ICE would be operated at low torque demand which generally is when cruising at lower speeds, at moderate speeds on level and slight downgrades, and at higher speeds on steeper downgrades.  This is basically like a hybrid operates until charge depletion requires ICE to come on at higher torque to charge HVB and to propel the car.  So, between plug ins, one would want to use EV wall charge on stretches of the road best suited for its efficient use which I doubt is going uphills.

I was thinking that using the heater to cool the WT down is a waist of heat energy/fan electricity that wouldn't be made if EV is used for a short time like a minute at a time to cool down ICE.  In that way all the heat energy the ICE makes is used to turn the wheels and charge the HVB. Running EV for a minute will cool down the ICE 5-10*F and then you could run the ICE for 5 minutes and repeat. This would only be necessary when going up hills. If you could combine ICE and EV together for an extended period of time going uphill you could keep the ICE from getting hot but the HVB temps would go up so you would need to monitor that too.

 

Paul

[plus 3 golfer]

10 hours ago, ptjones said:

I was thinking that using the heater to cool the WT down is a waist of heat energy/fan electricity that wouldn't be made if EV is used for a short time like a minute at a time to cool down ICE.  In that way all the heat energy the ICE makes is used to turn the wheels and charge the HVB. Running EV for a minute will cool down the ICE 5-10*F and then you could run the ICE for 5 minutes and repeat. This would only be necessary when going up hills. If you could combine ICE and EV together for an extended period of time going uphill you could keep the ICE from getting hot but the HVB temps would go up so you would need to monitor that too.

 

Paul

OK, but I'm not sure one wants to use a "cannon" (the Escape PHEV powertrain and HVB) to remove a little bit of heat when a "pea shooter" (a blower motor and maybe an auxiliary electric pump) does the job as my guess is that the cannon is far less efficient than the pea shooter. 

 

Look at it this way.  At a constant speed going uphill or on level ground with ICE (no charging), ICE runs at the same rpm.  But the torque requirements are higher going uphill than on level ground.  Thus, when going uphill more fuel is burned but the efficiency of ICE is likely better because ICE will be operating at a higher point on the BSFC curve than on level ground for the same rpm. 

 

Now an electric motor also has torque vs speed efficiency maps.  Below is an efficiency map of an electric motor (don't know what car) but it is a larger motor than in the Escape (C-Max 88 kW motor is rated at 240 Nm at low rpm) .  Note how the motor can supply constant high torque at range of low rpm and then the torque curve drops as rpm goes by the end of the constant torque portion.  So, one can see that at high torque and high rpm (like going uphill at interstate speeds), the efficiency of the electric motor will likely drop out of the optimal efficiency range.  For example, let's say that the torque requirement going up hill is 235 nm and the rpm is at 6500 rpm which might be a speed of around 60 mph depending on gearing.  The motor is operating at about an efficiency of 93% or 2% below it's best efficiency at 95%.

 

So, if one would switch to EV now mode going up a hill, there is a good chance that one has lost  2 % in efficiency or more depending on the hill from using EV on level and especially on slight downgrade highways where the torque requirements would likely fall in the dark red 95% range.  

 

 

Edited May 6, 2020 by Plus 3 Golfer

[ptjones]

I was trying to figure out a strategy to use the HVB/EV 30+ mile range of the 2020 FEHP  effectively. Anytime you use the EV Mode the ICE WT is going to go down so it makes no sense to use it at the beginning of a trip when you want to get up to operating temps as quickly as possible. That leaves using it during or end of trip. During the trip you would only use it to bring temps down from high end of operating temp range, you wouldn't want to get below operating temp range. Using it at the end of trip would work as long as you didn't to turn the ICE back on. Another consideration would be how much charging can you do when stopped.

 

Paul

[plus 3 golfer]

53 minutes ago, ptjones said:

I was trying to figure out a strategy to use the HVB/EV 30+ mile range of the 2020 FEHP  effectively. Anytime you use the EV Mode the ICE WT is going to go down so it makes no sense to use it at the beginning of a trip when you want to get up to operating temps as quickly as possible. That leaves using it during or end of trip. During the trip you would only use it to bring temps down from high end of operating temp range, you wouldn't want to get below operating temp range. Using it at the end of trip would work as long as you didn't to turn the ICE back on. Another consideration would be how much charging can you do when stopped.

 

Paul

Exactly,  you would want to use charge between wall charging.  But, if you don’t mind the heat inside the cabin from using the heater core to reduce WT going uphill, you will likely get better overall efficiency by fully using EV when cruising under flat / downhill conditions where torque is lower rather than using EV Now on steeper hills where torque demand is higher.  
 

It would be interesting to record data on the same highway trip with hills several times, experiment with different strategies for using EV now, and then analyze the data.  I believe with enough data one could develop “efficiency curves” for ICE and EV and then when driving by monitoring real time data and current road conditions adjust use of EV. But I likely won’t buy a PHEV to try / do such.  I think we talked about this prior (years ago) as to look ahead algorithms for FEVs and PHEVs to anticipate route conditions to optimize  real time use of HVB.capacity,  ICE and EV over the trip.  

[ptjones]

I agree with your Post, but using EV on level ground and especially downhill it will be hard to maintain best operating WT.  Also downhill if you can use Neutral/coasting is more efficient. I wonder if there is a way to use EV assist going uphill so the ICE wouldn't heat up as much. I have seen this happen when I have a high SOC like above 50%.

 

Paul

[fbov]

There's more to maintain than just WT in the the Escape Hybrid...

 

I had a long, downhill run earlier today, starting with WT in the normal range from ICE use coming up one side of the hill. WT didn't change much during the downhill, but at the bottom, starting ICE put the car went into "cold start" mode where ICE power output is limited for ~15 seconds, and heavily supplemented by EV. My understanding is that it's a catalytic converter temperature issue, as it goes away fast from a true cold start. C-Max does something similar, but I don't recall it ever reverting once warmed up. 

 

Stay well,

Frank

[ptjones]

Well with the Corona Virus slowing things down and 22 days since last fill up I ended up with 50% City, 58.8 mpg/776.2 mi./ 13.2 gal. the Best MPG in year and a half.? I could have made it to 800 Miles with about .7 gal. left.

 

Paul

[ptjones]

Filled up today 54.6MPG , 13.1 gal and 716 mi. with some A/C and rain.  This included trip back from Knoxville, TN and and round trip to Atlanta.

 

Paul

[ptjones]

It is interesting that MPG's keep going up with temps(88-94*F), lunch time I went up to Atlanta and back(48 mi. one way on I-85/I-20) not using A/C and front windows open a couple of inches. I averaged 59.5 mpg going up and 63.5 mpg going back in medium traffic, no stop and go. My tank averaged started with 59.5 mpg and ended with 60 mpg/ 323 mi./ 212 mi. EV. It is amazing how much MPG's are affected by outside temperature.?

 

Paul

[takingittothemax]

6 hours ago, ptjones said:

It is interesting that MPG's keep going up with temps(88-94*F) ... not using A/C and front windows open a couple of inches.?

 

I'm sweating just thinking about driving in that type of heat without aircon.

[fbov]

Check your tire pressures. Mine are still at placard pressures, yet I've been running 40 psi when driving in 90F air temperatures on roads that are far hotter. I calculate about a 5% reduction in rolling resistance as a result. Your tires are probably pushing 55 psi...

 

And air density is a factor in the drag force equation, so you're getting some benefit there. Finally, I think  warmth also helps bearings, if only to reduce the viscosity of the grease. If you've ever spun a wheel in winter, you know what I mean. 

 

Stay well,

Frank

[ptjones]

I have noticed an interesting phenomena where the ECM changes the fuel map to make the ICE run cooler/richer when I allow the WT get above 230*F for three times or more. I see a drop of 10-15*F WT temp and it doesn't seem to make much of a difference in FE.  Also It doesn't  go back to the leaner map when WT cools down. I have to turn off the ICE to reset it, I normally try to keep the WT temp below 229*F by using the defrost button to cool it down to 215*F which takes 15-20 sec.. If I take my partial cover off the bottom Grill Cover it drops temps by 5-10*F so I'm running 210-220*F range.  Middle Grill Cover is always on. Last two days I made a trip up to Maryland on I-85/95 and back averaging 53.5 mpg with some rain and A/C.

 

Paul

[ptjones]

I thought I would bring this back for  new members to show what can be done to improve MPG's.

 

Paul

[joshg678]

My 2016 SEL has 62,300 miles on it, currently up to 48.6 MPG, i was about to cross 48.8 before winter hit and just went down to 48.6 the other week.  I'm hoping to get 49 by next fall.

I would be higher, but i have lots of spirited driving, and i like to have some heat.

My Dad just traded in his 2016 SE for 2022 FEH Plugin.  I'm going to keep my C-MAX at least till 100k, then maybe I'll go full EV (Tesla or Rivian) 

[ptjones]

Sounds like you are doing a good job.?

 

Paul

[Chicago]

I am thinking about adding the tire aero dams to my 2013 Hybrid. Was there any final-ish determination of how much of a difference they made to fuel economy?

[ptjones]

I added them to my car and I don't remember any improvement. Grill Covers are worth 2-4 mpg and wheel covers 2 mpg and they cost less.

 

Paul

[JB22]

Hello everyone,

I am a new c-max owner end am enjoying most everything about it. Just a quick question, where could I get a battery level indicator and engine temp indicator like in Paul's video? Any help of advice is always welcome. Thanks 

[ptjones]

I use a ScanGaugeII, most Auto Parts places have them or you can do a Google search. We do have info on the codes for the CMAX posted here.

 

Paul

[ptjones]

I have had a number of members contact me about Grill Cover kits availability and I do some parts like a couple of Grill Cover sets, but not the Velcro fasteners. I was wondering if there was anyone that would be interested in taking over making them. I have the templates and instructions for installing them. You can PM me if interested.

 

Paul 

[ptjones]

I was hoping someone in the  CMAX forum would be interested in taking over for me making Grill Covers for those that can't make their own. It would be a shame not to have them available for New Members.

 

Paul

[Boselka]

Thank you @ptjonesfor all your info on this topic. We have a 2016 Energi and have implemented most of what you have recommended. Luckily we don’t have that long of a drive for work so even now we still have less than 60k miles on our energi. Currently our average MPG over the lifetime of our energi is 67.8 mpg. We have taken several road trips before, but we are about to embark on the largest road trip yet 4,000 miles over 10 days. So hopefully we will get some great MPG during our trip. We only have the grill aero shields on though.