Fuel Saving Tips and Tricks Part 1

[plus 3 golfer]

Probably not enough to compensate for the premature tire wear you will get on a set of $800 tires!

Why do you say that? Any facts?

 

I have never experienced premature wear from increasing tire pressure above the manufacturer's recommendations and I've been doing this for about 20 years.  I haven't read that anyone else has either. In fact, my tires wear more evenly across the tread and hence last longer with increased pressure.  The only downside I've noticed is harshness of ride in some vehicles.  Handling improves with increased pressure.

 

I have been running about 90% of sidewall maximum cold pressure in MBs, Nissans, Toyotas, VWs and now my Ford.  Currently, I have 45 psi in my C-Max instead of the recommended 38 psi.  

 

As far as FE increase, I would expect that FE might increase slightly with higher tire pressure but it would be difficult to quantify.  Going from 38 psi to 45 psi might result in a 6% decrease in rolling resistance (per an old Firestone study / formulae).  But since the rolling resistance drag is a small part of total drag on a car especially at higher speeds, I wouldn't expect any more than a few tenths of a mpg improvement which would be very difficult to quantify in normal everyday driving.  I know there are those hypermilers that claim a significant increase in FE by inflating tires up to or even beyond Max. cold pressure but they also likely do not drive very fast. :)

[Generalbeluga]

Check out this link and let me know what you think.  

 

http://www.popularmechanics.com/cars/news/4199963

Edited January 10, 2013 by Generalbeluga

[C-MaxJaxon]

The link has some extra trailing characters that causes a not found error.

 

My policy has been to stay within 10% of the manufacturer recommended pressure. I tried 40 psi briefly, but the already-firm ride was less comfortable and returned to 38.

[plus 3 golfer]

Check out this link and let me know what you think.  

 

http://blog.tirerack.com/blog/where-the-rubber-meets-the-road/how-tire-pressure-impacts-tread-wear 

That is a generalized statement.  

 

Todays modern tire / tread design doesn't "balloon" in the center like the old bias ply, non-steel belted tires did when overinflated.  Increasing pressure keeps the sidewall stiffer and thus there is less sidewall deflection in normal driving and especially in cornering such that the tire edges won't wear as fast.  I have always found that if I inflate to recommended pressure, the edges wear out faster than the middle.  Increasing pressure seems to balance tread wear for me. 

 

Again, I have not seen anyone post on forums that say that when they increase pressure above recommended, that the center wears out faster than the edges.

[Generalbeluga]

Sorry that the above link did not work properly.  See if this one is better:

 

http://www.popularmechanics.com/cars/news/4199963

[mtberman]

I usually don't chime in on tire pressure threads, oil change threads, or "octane" threads becasue there is so much mis-information out there about these topics. Usually the best advice is usually to just follow the manufacturer's recommendations.

 

Regarding tire pressure, I admit that I used to think that running a few pounds more pressure made a difference. I no longer feel that way. I've tested this in several different cars and it was my experience that it just created more tire noise and/or made the handling worse.

[PWBarrett]

OTOH, never assume that the manufacturer, dealer, or tire store put in the correct pressure.  I've had them come back way low and way high.

I think one tire store left in the high pressure they used to set the bead on the tire.

My C-Max was close, but a little low at 36 when I got it, so I went up to 39 all around.

[ptjones]

You are suppose to check tires when they are cool. One time I checked mine and the sun was shining on one tire and it was couple of psi higher. That makes it a little harder.  

[DozerBob]

50+ MPG the easy way! After almost 3 weeks of 120 mile round trips to work I'm happy to report a consistent 50+ mpg, without the plugin feature. That's right, using EV-Later mode! On the freeways of Los Angeles and Orange County.  I'll try to explain how and why this works.

This first picture shows me at the start of my drive with battery capacity at 28 miles

I've got 28 mi Electric to use if I want and am at 1983.4 total miles on the car.

     When I got in my car after charging all night it read 25 miles, but after driving down a short hill it regenerated to 28. I switched to EV-later after taking the picture and left it there for the whole trip to work.

Here are my thoughts to consider.

1. I want to get the best gas mileage I can possibly get.

      Running on Electricity gives me the best mileage possible, therefore during this drive I'm going to try to travel as far as I can on Electricity especially when the  electric motor is the most efficient.

      The Electric motor is not very efficient going uphill. It takes more juice to push this car uphill due to its weight.

2. The gas engine gets bad gas mileage, but it can accelerate you uphills and increase your speed and charge your battery. 3 good things. What you don't want to do is cruise on the gas engine. I don't let it run for more than 1 minute at a time, If I can help it. You have the control. It's in your right foot. Use the Empower mode Display and your right foot to control the throttle. Don't use cruise control.

 

I'm going to call this technique, "Surfing". Just like in surfing, You use the waves to propel you. You will be using the waves, or small hills to decide when to use the ICE and when to go EV-Auto and "surf" down the hills.

 

 

      Get the car up to 62 and back off the throttle until the blue threshold comes on. Then don't let the center of the bold blue performance indicator get past it so as to stay in electric mode, easing off the throttle a bit as the Threshold Indicator slowly comes down. When I've slowed to 55 or so, I step on the accelerator and increase my speed, taking about 30 seconds to a minute to get back to 68. That way I've given the ICE time to charge the hybrid battery back up so when I go to electric mode, the Threshold indicator will stay at about the second line on the KW indicator longer. That's what I do on flat stretches of road.

       Highways in the cities are not flat. There are undulations in the terrain caused by overpasses and underpasses, They are called "vertical curves" and are the result of elevation changes. Overpasses are usually a mile or so apart as they cross over roads below. Sometimes the freeway will go underneath a road and you will descend in elevation to go underneath a bridge.  

        Now Here's the "Surfing" trick, try to eyeball the road ahead so that you are at the top of an overpass when you are at 68 and you are backing off the throttle to go into electric mode. The electric motor is more efficient going downhill, even slightly and you can maintain your speed longer because it takes less KW or juice to go downhill. The C-Max is a heavy car and it's own mass going downhill is a big plus. The longer you can run the electric motor, the higher your mpg will be simply because electric mpg is way higher than using the ICE. That is the crux of getting higher mpg. At the end of your trip you should see a definite increase in the percentage of EV-Mode used.

      Now if you see the road ahead is going uphill for an overpass, time it so you are firing up the ICE to propel you uphill and increasing your speed to the top.

If all you do is run the gas engine from the bottom of the hill to the top, and go electric from the tops down you will increase your mileage.

I ran 63.6 miles total 32.6EV and got 50.2 mpge in EV-Later mode

The 28 miles on the battery indicator was reduced to 24 even though I was in EV-Later the whole way.

Edited March 2, 2013 by DozerBob

[C-MaxJaxon]

      Now if you see the road ahead is going uphill for an overpass, time it so you are firing up the ICE to propel you uphill and increasing your speed to the top.

 

I've never agreed with the idea of increasing speed on an uphill. I think it's more efficient to maintain or slightly drop speed on the incline and then slowly ramp speed back up on the flat or downhill.

[ptjones]

DozerBobs  Does ICE charge plugin battery? I made a round trip yesterday very hilly with 38deg.F going out and 54deg.F coming back.The average for both legs was 48.5mpg for 72.6mi with 44.5miEV or 61%. average speed 50-55mph, 5mi regen,1.4gal and 98% brake Score. Check your odometer with GPS, It looks like maybe everyone is getting 1.5% better MPG than actual calculated MPG.

I was wondering if anyone has gotten more than 608.6mi on 12.87gal?

[ptjones]

I've never agreed with the idea of increasing speed on an uphill. I think it's more efficient to maintain or slightly drop speed on the incline and then slowly ramp speed back up on the flat or downhill.

I'm thinking you might be right on that, That's the way usually do it.

[DozerBob]

  Yes, the ICE will regen the hybrid battery. watch for the ^ symbol on the top of the battery symbol showing charge. As long as your not stomping on the accelerator, you'll charge the battery.  In fact, on my Energi, I've run the plugin portion of the battery down to 0 and then went about 20 miles on a gradual downhill stretch, Ortega Highway here in So. Cal. and when I got to the bottom the battery symbol had gone back to the 3D battery symbol and it had 4 miles of charge gain back on it. Here is a great link to info on the differences and operations of both hybrid and Energi batteries.

http://www.sae.org/mags/aei/11705

    Here's my thought on increasing speed on the incline.  The ICE is rated @ 144 horsepower at 6000 rpm. Total of 188 horsepower with the Electric motor  engaged.

By running the ICE on the uphill you have the strongest propulsion doing the work. Also by increasing your speed slowly up the hill and then backing off the throttle @62 at the top is like giving a batter a floater over the middle of the plate. Don't you agree that the best scenario for our car is at the top of a hill with a full charged hybrid battery, speed of 62, then going into Electric mode so as to have the greatest momentum to come down the hill with my mass of 3600 pounds to give the electric motor it's sweetest chance to do what it does best, cruise down hill extends your range and requires less KW to maintain speed which increases the percentage of your trip in Electric mode. Doing that is where you get the extra mpg. More miles spent @ 100+ mpg in electric than @ 20 mpg or so with the ICE running. I'll continue to take pictures of my trip to work mpge in EV-Later mode for future updates on "Surfing" technique. In my previous post the second picture from the bottom shows the mpge of 50.2 after a trip of 63.6 miles. Last pictures shows the plug-in battery still has a charge of 24 miles on it to go.

Edited January 21, 2013 by DozerBob

[nsteblay]

I think the CMax's achilles heal is the ICE alone doesn't get very good gas mileage.  Good MPG on the CMax requires EV miles.  The amount of EV miles one gets on a trip is dependent on many variables, hence, the wide range of results people experience. 

 

I took my total miles traveled to date (4528.5) and divided by the lifetime reported MPG (35.5) to get the number of gallons consumed (127.6).  I then calculated the number of miles the ICE actually was running by subtracting the EV miles from the total Miles (4528.5 - 1547.6) to get total ICE miles (2980.9).  I then calculated ICE MPG by dividing ICE miles by total gallons used (2980.9 / 127.6) to get 23.4 MPG.  I think I did the math correctly.  I live in cold Minnesota which lowers my overall MPG.

 

I would be curious as to what others are getting in MPG from their ICE.  If results are fairly consistent the combined ICE / EV that happens at high speeds and fully charged battery must be insignificant.  With the CMax it appears to be an either / or proposition.  Good gas mileage is directly related to the amount of time spent in EV.

 

Toyota with the Prius has made it far more efficient using its gas engine.  I would imagine that riding on gas alone it gets in the low 30's.  Toyota then focused on the combined gas / electric to return even higher numbers.  The Prius will only allow EV mode up to 25 MPH.  The things you sacrifice in the Prius are looks (bullet design), interior room (lower profile), acceleration (smaller gas engine and electric motor), and you pay more.  Honda took a similar approach with the Insight.  There is less variability with these cars even driving at higher speeds (65 - 70 MPH).

 

Fuelly has the CMax at 38, and the Prius and Insight at roughly 45.  I am OK sacrificing the 7 MPG for looks, comfort and ability to accelerate.  My wife and I test drove the Prius before buying the CMax.  Neither of us liked the styling or lack of power.  The CMax is cheaper.  I won't make up the difference with the 7 MPG delta.

[plus 3 golfer]

Your math is correct but I don't see the logic in the calculated number. But maybe I'm missing something.  Anyways, my lifetime is 40.4 mpg and the calculated number is 27.0 mpg.  And what about the regen miles?  

 

Ice runs and burns fuel to charge the batteries and to propel the car. So, the calculated number is not a calculation of the FE of ICE.   What would a higher calculated number mean vs a lower calculated number?  The slower you drive the more EV miles will likely be accumulated.  Drive 70 mph and there will be virtually no EV miles accumulated.  So, my initial guess would be that a higher calculated number means one drives faster and a lower number means one drives slower than someone else everything else being the same.  But everything will likely not be equal (just look at fuelly FE number). 

 

And, I'm not sure your statement about the Prius being "far more efficient using its gas engine" is correct at all.  A smaller engine and lighter car will almost always be more fuel efficient than a heavier car with a more powerful engine.  Load a Prius V with an additional 366 pounds and the standard Prius with 598 pounds of additional weight and the FE numbers are likely to fall dramatically (maybe lower than the C-Max).  Then after loading up these cars with additional weight, see what the performance is like - my guess rather dismal compared to the C-Max.  Point is if one wants FE buy an insight or Prius.

 

Also, at 65-70 mph aerodynamics will be more of a factor in FE than at slower speeds. So, a Prius with a Cd of 0.25 vs a C-Max of 0.30 will have significantly less aerodynamic drag and hence not suffer as much of a reduction in FE due to drag as a C-Max at high speeds.  Again, it's all about understanding what one is buying when choosing whether to buy a Prius vs C-Max.  If you want to maximize FE at high speed buy the Prius. 

 

I did look at these variables plus others when choosing a C-Max over a Prius and bought the C-Max knowing I was not going to get Prius like FE.

[nsteblay]

Plus 3 Golfer thanks for the reply.  

 

The fact that you get 27 MPG with the ICE shows that the combined EV/ICE at high speeds (above 63 MPG) does improve the gas mileage.  I am not sure how to quantify it but it would be interesting to know the gains one gets from the combined EV/ICE at full charge and driving at 65-70 MPH.  The big gains that could get MPG to the EPA 47 mostly come from running in EV mode exclusively.  Given that the EPA tests are all below 60 MPH I think this is a safe statement.

 

I believe regen miles are an estimate of battery power (in miles) saved through breaking.  These numbers don't play into MPG calculations directly.

 

In talking about a Prius being more efficient I continue to stick by my statement.  Yes, engineered efficiency includes car weight, aerodynamics, tire size, etc.  Ford chose not to replicate that approach but produce a car with styling and acceleration - an appropriate tradeoff for some.

[plus 3 golfer]

I still don't see the point of this calculated value. There are simply too many variables to draw any conclusions.  

 

Brake regens recharge the battery like ICE and do affect FE.  The calculated value removes total EV miles but does not removing the fuel saved by regen miles or the EV miles associated with regens.  So the more "efficient" someone is in applying the brakes (recharging the battery through braking), the less fuel is used by ICE in recharging the battery. So, the calculated number through both fuel used and EV miles is affected based on how efficiently one uses the brakes.  Just another variable in the FE game.

 

We know the Prius gets better FE than the C-Max for several of the reasons I stated.  I guess I still am not sure what you are getting at.  I thought you were trying to imply the Toyota engineers get better efficiency from their hybrid / engine combination than Ford with the C-Max (efficiency = energy input to engine / energy output to drive wheels). If that's the case, you've made no convincing arguments to support it.  Otherwise, why even bring Prius into the picture.  You have to compare apples to apples which we really can't do for some of the reasons I stated.  

[PWBarrett]

I'd like to see a mode available where the battery would only be charged via regen and via engine-braking during deceleration and hill descent.  Getting the recharge load off the ICE would put it in the high-mileage mode that's been observed.  You'd still get the benefit of startup assist from energy captured during regen.  I have a feeling that the ICE is getting a bad MPG reputation when it's the recharge that's eating a lot of it.

There's a clear win in recapturing energy that would have gone to heat with normal braking, but using the engine to charge the battery can't be all that efficient.

Just my $0.02 worth.

[plus 3 golfer]

I'd like to see a mode available where the battery would only be charged via regen and via engine-braking during deceleration and hill descent.  Getting the recharge load off the ICE would put it in the high-mileage mode that's been observed.  You'd still get the benefit of startup assist from energy captured during regen.  I have a feeling that the ICE is getting a bad MPG reputation when it's the recharge that's eating a lot of it.

There's a clear win in recapturing energy that would have gone to heat with normal braking, but using the engine to charge the battery can't be all that efficient.

Just my $0.02 worth.

The use of ICE to charge batteries makes sense under certain conditions like when ICE could be running at the most efficient areas of the BSFC curve if charging.  The stored energy from such efficient charging will be used when ICE would have had to run in very inefficient areas of the BSFC curves (like acceleration and lower speeds).  Even with the charging and EV mode operational losses, overall efficiency of the hybrid system improves with such operation.  

 

Also, I have run tests at 70 mph and the amount of recharge from ICE was minimal even with a 55% or so battery level (level was virtually constant within +- a few %).  In other words, from an efficiency standpoint, the PC algorithm chose to not run ICE harder to charge the battery at 70 mph to its full level likely because it was not going to be an efficient use of energy.  Also, once coasting down to a slower speed from 70 mph (and also going down steeper hills) ICE would shut down and there would be regeneration from such coasting which would increase the battery level to near 100% very quickly.  So, the system does capture energy when going down hill and also when slowing down not using the brakes.

 

One more point, there is no engine braking going down hill or coasting to a stop.  The engine is not spinning (rpm are zero).  The "braking" one feels is the motor being used as a generator and recharging.  When one engages the "grade assist", engine braking will occur along with the generator "braking."

[PWBarrett]

When I used the term engine-braking, I meant the motor being used as a generator while coasting, not traditional ICE engine-braking.

 

So what's the explanation for the high-MPG ICE mode that can occur when the battery is fully charged?

[plus 3 golfer]

When I used the term engine-braking, I meant the motor being used as a generator while coasting, not traditional ICE engine-braking.

 

So what's the explanation for the high-MPG ICE mode that can occur when the battery is fully charged?

There is no magic. Without real-time hard data one questions what people believe they are seeing / doing. If the battery is fully charged, all ICE energy is going to the drive line. So, FE during that time could be higher than when Ice is charging. The algorithm can't predict future conditions and thus there certainly could be speed, charge level, and other conditions where after the fact it may appear to make the wrong choices. Edited February 19, 2013 by Plus 3 Golfer

[roninsd]

Fuelly has the CMax at 38, and the Prius and Insight at roughly 45.  I am OK sacrificing the 7 MPG for looks, comfort and ability to accelerate.  My wife and I test drove the Prius before buying the CMax.  Neither of us liked the styling or lack of power.  The CMax is cheaper.  I won't make up the difference with the 7 MPG delta.

 

Let's not forget that the fuelly.com stats for the Prius come from over 1800 Prii, over many years, while the C-Max hybrid has less than 100 registering their gas usage, and that's been for less than a year.  This isn't a slam against, the Prius, but it's like comparing ripe Apples with green lemons.

 

Also, regarding mileage from ICE alone: I bought a hybrid so that I could use both!

[MacGyver]

The use of ICE to charge batteries makes sense under certain conditions like when ICE could be running at the most efficient areas of the BSFC curve if charging.  The stored energy from such efficient charging will be used when ICE would have had to run in very inefficient areas of the BSFC curves (like acceleration and lower speeds).  Even with the charging and EV mode operational losses, overall efficiency of the hybrid system improves with such operation.  

 

Also, I have run tests at 70 mph and the amount of recharge from ICE was minimal even with a 55% or so battery level (level was virtually constant within +- a few %).  In other words, from an efficiency standpoint, the PC algorithm chose to not run ICE harder to charge the battery at 70 mph to its full level likely because it was not going to be an efficient use of energy.  Also, once coasting down to a slower speed from 70 mph (and also going down steeper hills) ICE would shut down and there would be regeneration from such coasting which would increase the battery level to near 100% very quickly.  So, the system does capture energy when going down hill and also when slowing down not using the brakes.

 

One more point, there is no engine braking going down hill or coasting to a stop.  The engine is not spinning (rpm are zero).  The "braking" one feels is the motor being used as a generator and recharging.  When one engages the "grade assist", engine braking will occur along with the generator "braking."

 

I thought I felt that, despite my ford salesman telling me the direct opposite.

 

Got any numbers on which is most efficient? I would expect braking, hill assist, then coasting.

[finkins]

The use of ICE to charge batteries makes sense under certain conditions like when ICE could be running at the most efficient areas of the BSFC curve if charging.  The stored energy from such efficient charging will be used when ICE would have had to run in very inefficient areas of the BSFC curves (like acceleration and lower speeds).  Even with the charging and EV mode operational losses, overall efficiency of the hybrid system improves with such operation.  

 

Also, I have run tests at 70 mph and the amount of recharge from ICE was minimal even with a 55% or so battery level (level was virtually constant within +- a few %).  In other words, from an efficiency standpoint, the PC algorithm chose to not run ICE harder to charge the battery at 70 mph to its full level likely because it was not going to be an efficient use of energy.  Also, once coasting down to a slower speed from 70 mph (and also going down steeper hills) ICE would shut down and there would be regeneration from such coasting which would increase the battery level to near 100% very quickly.  So, the system does capture energy when going down hill and also when slowing down not using the brakes.

 

One more point, there is no engine braking going down hill or coasting to a stop.  The engine is not spinning (rpm are zero).  The "braking" one feels is the motor being used as a generator and recharging.  When one engages the "grade assist", engine braking will occur along with the generator "braking."

Hi there;

I am new in this endeavour, and am trying to learn as much as possible to increase milage figures. Just got my new C Max.

I am pleased to hear that when I am drifting down a hill, no ICE, no EV drain, that there is regeneration happening. Do I have that right?

All the talk seems to be around braking regeneration, not coasting recharging. Why is that?

If I need more than just "generator" braking downhill, am I better to brake, or engage the "grade assist" to provide engine braking, from an energy efficient standpoint?

[DR61]

Hi there;

I am new in this endeavour, and am trying to learn as much as possible to increase milage figures. Just got my new C Max.

I am pleased to hear that when I am drifting down a hill, no ICE, no EV drain, that there is regeneration happening. Do I have that right?

All the talk seems to be around braking regeneration, not coasting recharging. Why is that?

If I need more than just "generator" braking downhill, am I better to brake, or engage the "grade assist" to provide engine braking, from an energy efficient standpoint?

When you are completely off the accelerator pedal, there is light regeneration (the ^ symbol on top of battery is on).  That is not true coasting.  When you put the shifter into N, then you have true coasting with no regeneration.  In N only aero drag and bearing/tire drag is slowing the car.  You can try this on a flat road with no traffic: drive at 30 mph, lift off at some reference point, and note how far the car goes before it hits 20 mph.  Try it in D and N and you will see that you go many times farther in N before your speed drops to 20 mph.  It is sometimes useful to use N going downhill in gently rolling terrain to maximize coasting up the next hill, if traffic safety allows. 

 

If you need more than regen to control your speed going down a steep hill, I recommend first L, then Grade Assist.  The ICE may turn on to provide engine compression braking, but it will use insignificant or zero fuel.