Ford C-Max vs Prius after 1 year

[obob]

Consumer Reports 2015 models                    jetta tdi / energi / hybrid / passat tdi

 

0 to 30 mph, sec.    3.6 3.3 3.4 3.6  

0 to 60 mph, sec.    9.5 8.1 8.4 9.8  

45 to 65 mph, sec . 6.0 5.3 5.1 6.1  

Quarter-mile, sec.   17.3 16.4 16.6 17.6  

Quarter-mile, mph   83 89 89 82

 

Energi is the fastest except for 45 to 65

Edited November 4, 2014 by obob

[ptjones]

CR doesn't have a very good rep with this forum.  I suppose we could average several Magazines numbers and get a more accurate number.

                           Hydrid         Energi

Edmunds               8.1sec         7.8sec

Car & Driver           7.9sec     

Motor trend            8.2sec         8.5sec

Motor Week                              8.5sec

Adding these numbers with CR you get 8.15sec Hybrid and 8.22sec Energi, pretty much a tie. :)

 

Paul

[Husker4theSpurs]

Hybrids aren't designed for high speed driving and you would be better off with a WV Jetta TDI, on the down side CMAX gets 10-15mpg better in the city. BTW you can increase 2-4mpg by adding Grill Covers and Oil Pan Heater to CMAX. BTW if you have 50K miles and haven't had a battery problem you probably aren't going too. I have 77.6K miles and no battery problems. Keep in mind very few people have battery problems percentage wise. IMO :)

 

Paul

I understand hybrids don't do well at high speeds ... I was merely comparing my experience now to my experience with 3 Priuses. We have had the battery randomly discharge 4 times so we have experiences the battery problem.

[obob]

CR doesn't have a very good rep with this forum.  I suppose we could average several Magazines numbers and get a more accurate number.

                           Hydrid         Energi

Edmunds               8.1sec         7.8sec

Car & Driver           7.9sec     

Motor trend            8.2sec         8.5sec

Motor Week                              8.5sec

Adding these numbers with CR you get 8.15sec Hybrid and 8.22sec Energi, pretty much a tie. :)

 

Paul

 

I agree.  It is pretty much a tie.  I was just surprised because I also thought the added weight might be a factor at normal driving speeds.

[Smiling Jack]

I agree.  It is pretty much a tie.  I was just surprised because I also thought the added weight might be a factor at normal driving speeds.

 

True about the extra weight, but  - on the other hand - , the Energi has about 30 HP more (as a result of ability to deliver substantially more current to the electric motor); so, in some speed ranges it is definitely quicker.

[stevedebi]

The Passat is actually about 600 or so pounds lighter than my Energi. I'm not saying there is anything wrong with the C-Max or Energi, or anything especially "right" about the Passat TDI, just that the diesel is more suited to highway travel. I saw some comments here that indicated folks didn't comprehend how good a diesel can be on the road, and since I own both I thought I'd chime in.

 

I think my Energi is about 300 lbs more than the hybrid only C-Max. That is one hulkin' big battery back there...

 

I never accelerate my C-Max like that unless there is a safety situation where I need the speed. Which seldom happens with careful hybrid-style driving.

[drdiesel1]

The 2013 hybrid and Energi had different final drive ratio's. 2014's have the same 2:91 final drive ratio.

[stevedebi]

The 2013 hybrid and Energi had different final drive ratio's. 2014's have the same 2:91 final drive ratio.

What is the 2013 final drive ratio? Is that a software change? Technically the planetary drive doesn't have ratios like a conventional AT.

[kostby]

Final Drive ratio on our 2013 Hybrid SE is 2.57 as reported on Ford ETIS on 4/29/2014 for our 2013 C-MAX SE.

 

 

Or not. According to a recent post by Rachel of Ford Service, ETIS is not the official Ford site for North American C-MAX info.

Edited November 5, 2014 by kostby

[ptjones]

The 2013 hybrid and Energi had different final drive ratio's. 2014's have the same 2:91 final drive ratio.

 

What is the 2013 final drive ratio? Is that a software change? Technically the planetary drive doesn't have ratios like a conventional AT.

Last I heard was that it didn't happen, I believe someone checked Part#'s and they hadn't changed. I checked out FORDPARTS.com and all 2013-15 have the same Part# 7000 for the transmission. :)

 

Paul

[stevedebi]

Last I heard was that it didn't happen, I believe someone checked Part#'s and they hadn't changed. I checked out FORDPARTS.com and all 2013-15 have the same Part# 7000 for the transmission. :)

 

Paul

That is one reason I mentioned software. I think that the C-Max would be "programmable", rather than a different transmission. The hybrid transmission is completely different from a conventional transmission, which does have a "hardware" final ratio, based on the gearing.

[ScubaDadMiami]

I think that the C-Max would be "programmable", rather than a different transmission. The hybrid transmission is completely different from a conventional transmission, which does have a "hardware" final ratio, based on the gearing.

There was both a hardware and software change in the 2014 relating to the transmission. The 2013 had a software reprogram to closely match it, but we still have the previous hardware.

 

I am guessing that 2015 will be the year that Ford gets all of the last issues ironed out, and that they elected to perfect production of things before making any significant changes. That's just a total guess, but I have a feeling that it will go down this way in relation to quality of build and reliability. After that, Ford will be ready for whatever will come next.

[plus 3 golfer]

That is one reason I mentioned software. I think that the C-Max would be "programmable", rather than a different transmission. The hybrid transmission is completely different from a conventional transmission, which does have a "hardware" final ratio, based on the gearing.

This is what Ford said

 

Last I heard was that it didn't happen, I believe someone checked Part#'s and they hadn't changed. I checked out FORDPARTS.com and all 2013-15 have the same Part# 7000 for the transmission. :)

 

Paul

Look at 7H348A - the Auto Trans Transfer Drive Gear.

 

The part number is the same for 2013 through 2015 MY.  But there are two choices for MY 2013 and MY 2015 - one for the Hybrid 2.57 and one for the NRG 2.91.  But for 2014, there are 4 choices: 2 for build dates before 8/3/2014 and 2 for build dates after 8/4/2014.  However, the 2 choices before and after the build dates still show the same final drive ratios as MY 2013 for the Hybrid and NRG.   

 

So, based on the above either Ford didn't change the final drive ratios (and changed something else with the drive gear assembly around 8/4) or there are errors in the Ford Parts listings.

[stevedebi]

This is what Ford said

 

Look at 7H348A - the Auto Trans Transfer Drive Gear.

 

The part number is the same for 2013 through 2015 MY.  But there are two choices for MY 2013 and MY 2015 - one for the Hybrid 2.57 and one for the NRG 2.91.  But for 2014, there are 4 choices: 2 for build dates before 8/3/2014 and 2 for build dates after 8/4/2014.  However, the 2 choices before and after the build dates still show the same final drive ratios as MY 2013 for the Hybrid and NRG.   

 

So, based on the above either Ford didn't change the final drive ratios (and changed something else with the drive gear assembly around 8/4) or there are errors in the Ford Parts listings.

Interesting. I looked the part up, and the diagrams I saw are mostly for conventional AT. I guess that this limits the top revolution speed (or minimum speed, if you want to look at it that way). I didn't realize that the conventional hybrid and the Energi would have different capabilities.

 

So the CVT is infinitely variable up to the hardware maximum.

[plus 3 golfer]

Interesting. I looked the part up, and the diagrams I saw are mostly for conventional AT. I guess that this limits the top revolution speed (or minimum speed, if you want to look at it that way). I didn't realize that the conventional hybrid and the Energi would have different capabilities.

 

So the CVT is infinitely variable up to the hardware maximum.

Correct CVT infinitely variable within hardware constraints (includes MG1 and MG2 rpm constraints and the final drive gearing.  The best one could do (tallest overall gearing) is to put a holding torque on MG1 so that it does not spin when the engine is running.  Then, all engine rpms would be directed to the output shaft.  So, a numerically lower final drive ratio would yield lower engine rpm than a higher final drive ratio at the same vehicle speed. For highway cruising one wants to run ICE at the most efficient area of the Brake Specific Fuel Consumption map which is generally low rpm, high torque.  It's like up-shifting a  conventional transmission to a higher overdrive gear to lower engine rpm to improve FE.  This should be achieved in Negative-Split Mode Operation (from the Ford OBD System Operation Summary for Plug-in and Hybrid Vehicles):

 

Negative Split Mode

 The engine is on and the generator motor consumes electrical energy to reduce engine speed

 The traction motor can operate as a motor or a generator to make up the difference between the engine power and the desired power

 Typical highway mode

 Occurs when the engine needs to be on, the system can not be operated in parallel mode and the battery is charged near its upper limit

 

 

Prior to a PCM update of the Hybrid to increase the EV top speed from 62 mph to 85 mph, it was quite easy to get into negative split mode  by controlling the throttle and to stay in this mode for some time.  With EV operations now up to 85 mph, it harder to get into the mode (keeping the battery charged near its upper limit) as any slight decrease in power requirements can trigger EV operation at higher speeds.  

 

The different final drive ratio for the hybrid and NRG supposedly was to improve performance of the NRG given it's extra weight (larger HVB) such that both vehicles would be very similar performance wise.  My guess is the PCM algorithms for both the NRG and Hybrid are the same once the NRG enters Hybrid mode operation.  So, by numerically increasing the NRG final drive over the Hybrid ratio, the NRGs low end performance would be improved somewhat. 

[stevedebi]

Correct CVT infinitely variable within hardware constraints (includes MG1 and MG2 rpm constraints and the final drive gearing.  The best one could do (tallest overall gearing) is to put a holding torque on MG1 so that it does not spin when the engine is running.  Then, all engine rpms would be directed to the output shaft.  So, a numerically lower final drive ratio would yield lower engine rpm than a higher final drive ratio at the same vehicle speed. For highway cruising one wants to run ICE at the most efficient area of the Brake Specific Fuel Consumption map which is generally low rpm, high torque.  It's like up-shifting a  conventional transmission to a higher overdrive gear to lower engine rpm to improve FE.  This should be achieved in Negative-Split Mode Operation (from the Ford OBD System Operation Summary for Plug-in and Hybrid Vehicles):

 

 

Prior to a PCM update of the Hybrid to increase the EV top speed from 62 mph to 85 mph, it was quite easy to get into negative split mode  by controlling the throttle and to stay in this mode for some time.  With EV operations now up to 85 mph, it harder to get into the mode (keeping the battery charged near its upper limit) as any slight decrease in power requirements can trigger EV operation at higher speeds.  

 

The different final drive ratio for the hybrid and NRG supposedly was to improve performance of the NRG given it's extra weight (larger HVB) such that both vehicles would be very similar performance wise.  My guess is the PCM algorithms for both the NRG and Hybrid are the same once the NRG enters Hybrid mode operation.  So, by numerically increasing the NRG final drive over the Hybrid ratio, the NRGs low end performance would be improved somewhat. 

From what I can see the Negative Split Mode is bleeding off excess energy because the battery is full? It says "the generator consumes electrical energy". Also, they list a "parallel mode", but don't describe it with diagrams and an explanation such as they do for the Split, Series, and Electric modes.

 

I notice that the document diagrams of the Negative and Positive Split modes are identical from what I can tell.

[plus 3 golfer]

From what I can see the Negative Split Mode is bleeding off excess energy because the battery is full? It says "the generator consumes electrical energy". Also, they list a "parallel mode", but don't describe it with diagrams and an explanation such as they do for the Split, Series, and Electric modes.

 

I notice that the document diagrams of the Negative and Positive Split modes are identical from what I can tell.

I've monitored HVB State of Charge while in negative split mode and the SOC stays virtually the same. MG2 can generate the energy required to run MG1 as a motor with virtually no change in SOC.  See this post.  Also, attached is a good pdf on Hybrid transmissions.

 

This is how I summarize the various modes:

 

Series - speed is zero and engine is on.

Split - Positive - engine is on, engine power is split between charging battery via the generator and driving the car

Split - Negative - engine is on, engine power is split between the generator consuming power and driving the car

Parallel - Generator is stopped (not spinning), engine power and battery assist power (traction motor) driving vehicle.

 

The point I was making is that when ICE has to run because the HVB is above a threshold level, there is a physical lower rpm limit and it can be reached when MG1 acts as a motor slowing down ICE rpm.   A numerically lower final drive ratio should allow ICE to operate at a lower rpm and likely increase FE at highway speeds (even though MG1 may be consuming power). There is simply no other way that I am aware of slowing ICE rpm to put ICE at higher efficiency with the hybrid split transmission.   I think many of us were hoping that Ford would lower the final drive ratio and that might allow an improvement in highway FE perhaps at the expense of a drop in performance.  

Comparison of Hybrid Transmissions.pdf

[stevedebi]

Thanks for the explanations. I think this confirms what I have been saying - that if one gets to the negative split mode, the system bleeds off excess energy from the engine because the SOC is at "maximum".  However, I've yet to see this situation - in general, I see the SOC going up and down while at LA traffic speeds, even when the speed is consistent. I think I've seen it on a recent trip with a long downhill, where I forgot to switch to Auto mode in my Energi; the SOC got up to a certain state and didn't go higher, even though the energy was definitely positive.

 

For the Energi, I believe this is also correct, which is a waste, since Ford could have recharged the larger battery, but instead treats the Energi as if it were the normal C-Max while on the highway.

[Jus-A-CMax]

wait - r u saying in the energi it is not recharging the larger battery to its full capacity when downhilling? I always thought that the energi had a huge advantage when downhilling a super long grade to build & store more charge than a regular CMax. 

 

also in a negative split mode, the cmax is supersensitive to the slope of the road and will charge or use the batts on what, to the eye, appears to be a perfectly flat road. 

 

it was also so much better and higher in the ice high mpg mode aka negative split mode, when the limiter was on at 64mph. the 13b07 change to push the EV to 85mph seems to reduce the effectiveness of the ice high mpg, based on what i am seeing.

Edited November 7, 2014 by Jus-A-CMax

[stevedebi]

wait - r u saying in the energi it is not recharging the larger battery to its full capacity when downhilling? I always thought that the energi had a huge advantage when downhilling a super long grade to build & store more charge than a regular CMax. 

 

also in a negative split mode, the cmax is supersensitive to the slope of the road and will charge or use the batts on what, to the eye, appears to be a perfectly flat road. 

 

it was also so much better and higher in the ice high mpg mode aka negative split mode, when the limiter was on at 64mph. the 13b07 change to push the EV to 85mph seems to reduce the effectiveness of the ice high mpg, based on what i am seeing.

Once you go into EV Later mode, the reserve % doesn't change. The Energi will max out at 1.6KW. If you want to add to the main battery, you have to manually switch back to Auto or EV Now, at the appropriate time for charging conditions.

 

I've heard folks say that the main battery can "come back" from depletion on an extremely long downhill, but I've not seen that, and it must be some quirk of the system if that happens.

Edited November 7, 2014 by stevedebi

[plus 3 golfer]

Once you go into EV Later mode, the reserve % doesn't change. The Energi will max out at 1.6KW. If you want to add to the main battery, you have to manually switch back to Auto or EV Now, at the appropriate time for charging conditions.

 

I've heard folks say that the main battery can "come back" from depletion on an extremely long downhill, but I've not seen that, and it must be some quirk of the system if that happens.

 

Thanks for the explanations. I think this confirms what I have been saying - that if one gets to the negative split mode, the system bleeds off excess energy from the engine because the SOC is at "maximum".  However, I've yet to see this situation - in general, I see the SOC going up and down while at LA traffic speeds, even when the speed is consistent. I think I've seen it on a recent trip with a long downhill, where I forgot to switch to Auto mode in my Energi; the SOC got up to a certain state and didn't go higher, even though the energy was definitely positive.

 

For the Energi, I believe this is also correct, which is a waste, since Ford could have recharged the larger battery, but instead treats the Energi as if it were the normal C-Max while on the highway.

No, that is not a correct characterization of what happens. There is no bleeding off of ICE energy.  

 

Don't confuse energy with power or torque. Energy input is a function of fuel burned.  Energy output is the integrated instantaneous power over time.  The torque / power requirement can remain the same over time, but lowering ICE rpm can reduce fuel input. So, the efficiency of ICE improves - output / input increases.  Again MG1 acts as a motor using energy, MG2 acts as a generator producing energy.  The power requirements of ICE hasn't changed.  But what changes is the rpm of ICE and thus ICE operates more efficiently (uses less fuel because it's operating at a more efficient point on the BSFC map). If the torque / power requirements change (road load changes)  MG2 makes up the difference by either producing or using power.  

 

Again, this is no different that shifting a manual transmission from say 5th gear to 6th gear.  Road load hasn't changed.  But ICE efficiency likely improves and ones FE goes up running in a higher gear.  There is no bleeding off of ICE energy.  What changes is rpm goes down (same as Hybrid in negative split) and fuel use goes down because one is likely operating ICE on a more efficient point on the BSFC map. 

 

Again, the generator MG1 will use energy to slow engine rpm to increase ICE efficiency (road load requirements haven't changed) and the traction motor MG2 can use energy or produce energy to cover load variations to keep ICE at an efficient point on the BSFC.  SOC as I've observed, recorded, and graphed in negative split mode over about a 4 mile stretch with eco cruise at 55 mph started at about 56% and leveled off at 58% in the first 1/2 mile or so and remained at about 58%.  I couldn't drive any further in negative split because I was approaching a red light.  

 

What's important is for the negative split algorithm to operate the vehicle most efficiently. The efficiency of the Hybrid transmission can and likely goes down in negative split mode.due to additional energy losses in MG1, MG2, Inverter and so forth.  But an improvement in ICE efficiency by lowering rpm should more than offset these energy losses.   FE thus can go up.

 

Also, I think it was member Valkraider that would partially fill his Energi "big" battery when going down a mountain from skiing. He had pics that showed starting at the top with energy only in the "little" battery.  After 16 miles of mostly downhill IIRC he had around 4 kWh in the big battery.

[stevedebi]

No, that is not a correct characterization of what happens. There is no bleeding off of ICE energy.  

 

Don't confuse energy with power or torque. Energy input is a function of fuel burned.  Energy output is the integrated instantaneous power over time.  The torque / power requirement can remain the same over time, but lowering ICE rpm can reduce fuel input. So, the efficiency of ICE improves - output / input increases.  Again MG1 acts as a motor using energy, MG2 acts as a generator producing energy.  The power requirements of ICE hasn't changed.  But what changes is the rpm of ICE and thus ICE operates more efficiently (uses less fuel because it's operating at a more efficient point on the BSFC map). If the torque / power requirements change (road load changes)  MG2 makes up the difference by either producing or using power.  

 

Again, this is no different that shifting a manual transmission from say 5th gear to 6th gear.  Road load hasn't changed.  But ICE efficiency likely improves and ones FE goes up running in a higher gear.  There is no bleeding off of ICE energy.  What changes is rpm goes down (same as Hybrid in negative split) and fuel use goes down because one is likely operating ICE on a more efficient point on the BSFC map. 

 

Again, the generator MG1 will use energy to slow engine rpm to increase ICE efficiency (road load requirements haven't changed) and the traction motor MG2 can use energy or produce energy to cover load variations to keep ICE at an efficient point on the BSFC.  SOC as I've observed, recorded, and graphed in negative split mode over about a 4 mile stretch with eco cruise at 55 mph started at about 56% and leveled off at 58% in the first 1/2 mile or so and remained at about 58%.  I couldn't drive any further in negative split because I was approaching a red light.  

 

What's important is for the negative split algorithm to operate the vehicle most efficiently. The efficiency of the Hybrid transmission can and likely goes down in negative split mode.due to additional energy losses in MG1, MG2, Inverter and so forth.  But an improvement in ICE efficiency by lowering rpm should more than offset these energy losses.   FE thus can go up.

 

Also, I think it was member Valkraider that would partially fill his Energi "big" battery when going down a mountain from skiing. He had pics that showed starting at the top with energy only in the "little" battery.  After 16 miles of mostly downhill IIRC he had around 4 kWh in the big battery.

I'm still not getting it. The generator kicks in to slow engine RPM? That is what the negative split mode is about? I don't see how that helps, as opposed to lowering the RPM by kicking in electric assist, since the SOC is full anyway. As you said, since the new hybrids will go EV up to 85 MPH, maybe it isn't that big a deal any more...

[plus 3 golfer]

The generator is run as a motor and thus speeds up.  Watch this video on the Prius hybrid transmission.  See if that clears up anything. The equation for rotational speed (from the document I attached and neglecting the internal gear ratios inside the transmission) is:  Speed _MG1 + Speed _MG2 = Speed _ICE

 

So, if MG2 is spinning at wheel speed and doesn't change and one wants to decrease ICE rpm, MG1 needs to speed up so that ICE  rpm drops (look at Fig 1 in the attachment). MG1 is attached to the sun gear, MG2 to the ring gear, and ICE to the planet carrier.  MG2 will act as a generator / motor to balance power requirements out as road load change to maintain speed. To much change in road load can kick in EV mode.  Of course one can also ease up on the throttle slightly to try to stay in negative split should road load increase say due to a slight increase in elevation.

 

To tie this into the Prius vs C-Max, the Prius EV mode operation is limited to around 40 mph (? IIRC)  So, the Prius should run in negative split a lot more than the C-Max. 

 

One more point I forgot to mention is that why not lower ICE rpm by kicking in electric assist? Because when ICE rpm drops due to electric assist so does load on ICE.  Thus, ICE is not operating as efficiently.   I think what is overlooked is that all energy in the hybrid comes from the fuel burned.  One does not want to use electric assist unless conditions require it or it improves overall  efficiency like lower speed acceleration from stop, larger changes in road load, harder acceleration and so forth.  Using electric assist to deplete the HVB for no efficiency gain doesn't make sense when one can take advantage of the hybrid transmission and keep ICE load up and lower rpm to improve overall efficiency.  You need to understand the BSFC map. 

Edited November 10, 2014 by Plus 3 Golfer

[Jus-A-CMax]

ok guys - friendly reminder to get back to the original topic at hand but feel free to start a new thread or piggy back off an existing thread on negative split mode discussions....:)

[jimdel13]

I am a 2005 Prius owner considering a 2013 CMax Hybrid.  After reading this forum I am not sure if I shouldn't look for a newer Prius.   If the battery issue was solved, I would definitely go for the CMax.

Jim