MPH vs MPG

[marshtex2]

MPH vs MPG

 

I made a nominally 200 mile trip twice in a day.  C-Max odometer = 206 mi., GPS = 210 mi

 

Trip 1, 8:00 – 12:00 am, 60 deg to 80 deg.  GPS moving average 53.8 mph.  C-Max puter = 51.2 mpg.

 

Trip 2, 4:00 – 8:00 pm, 80 deg to 60 deg.  GPS moving average 54.6 mph, C-Max puter = 48.1 mpg.

 

Driving technique: On trip 1 I let it slow down to about 50 mph on the up-hill parts.  On trip 2 I mostly put in on Eco-Cruise at about 57 mph and let it go that way up hill and down hill.

 

Result: At speeds around 54 mph a 1.5% increase in speed gets a 5.9% increase in fuel consumption.  Worth it?

[stevedebi]

MPH vs MPG

 

I made a nominally 200 mile trip twice in a day.  C-Max odometer = 206 mi., GPS = 210 mi

 

Trip 1, 8:00 – 12:00 am, 60 deg to 80 deg.  GPS moving average 53.8 mph.  C-Max puter = 51.2 mpg.

 

Trip 2, 4:00 – 8:00 pm, 80 deg to 60 deg.  GPS moving average 54.6 mph, C-Max puter = 48.1 mpg.

 

Driving technique: On trip 1 I let it slow down to about 50 mph on the up-hill parts.  On trip 2 I mostly put in on Eco-Cruise at about 57 mph and let it go that way up hill and down hill.

 

Result: At speeds around 54 mph a 1.5% increase in speed gets a 5.9% increase in fuel consumption.  Worth it?

In general, I think my time is worth the extra expense. I generally go near the speed limit, which here in LA is usually 65. Traffic generally moves 5-10 MPH faster.

[Podivin]

Anyone slowing down to 50 mph on what I assume is a 60 mph road (based on the speed from your other trip) is going to be a truly annoying person to follow, plus forcing more people to pass him and/or jam up behind him, thereby interrupting the overall traffic flow. I think that's one of the ways road rage begins.

 

That aside, on your 200 mile trip you saved ~62 cents, using a fuel price of $2.50, and it took you about 10 minutes longer.

If you value your time at more than $3.72 per hour (10 minutes * 6 = 1 hour, 62 cents * 6 = $3.72) then no, it's not worth it.

 

For me, it's not worth it. On the highway I run at the speed the law allows on that stretch of road and I don't sweat the gas mileage. In town I don't accelerate hard, I try to anticipate stop lights and coast when I can (while still maintaining a reasonable speed for the traffic around me), and my overall average is 45 mpg. I figure what I 'lose' on the highway I make up for in town.

[Automate]

MPH vs MPG

 

I made a nominally 200 mile trip twice in a day.  C-Max odometer = 206 mi., GPS = 210 mi

 

What about the elevation of your start and end locations?

[plus 3 golfer]

In general, I think my time is worth the extra expense. I generally go near the speed limit, which here in LA is usually 65. Traffic generally moves 5-10 MPH faster.

Me too.  I keep up with the flow which in light traffic around Phoenix is around 70-72 mph on the 65 mph freeways.  For me, time not money is the limited resource. 

 

Around town on a 30 mile typical shorter round trip, I can take the parallel streets to the freeways rather than the freeways for about 20-22 miles of the 30 miles, but using the side streets adds about 20-25 minutes to the round trip (more if I hypermile).  In normal driving, I will get over 50 mpg on the side streets (and have demonstrated over 60 mpg if I really slow down and hypermile with average speed of  around 25-27 mph) but the fuel savings amounts to about $0.30 total or a penny a mile but costing 40 seconds a mile in time.  So, assume 10,000 miles per year of such driving, I can save $100 in fuel but waste 400,000 seconds in time (111 hours).  This is a conservative estimate as taking the side streets for our longer local trips would result in proportionately higher wasted time.

 

I've also reported a 4000+ mile trip to PA and back a couple of times to illustrate several points.  On the trip East I got overall 40.4 mpg - door to door with an average speed of 68.4 mph (gps miles / gps moving time). My average speed on interstates (about 1600 miles) was 72.3 mph.  On the trip back home, I averaged nearly 74 mph on interstates mainly because I drove very little during darkness so I set eco-cruise about 1-2 mph higher. I also battled a strong quartering wind from MO into AZ and rain in AZ high country and my overall return mpg dropped to 38.3 mpg.  Overall, door to door round trip of over 4070 miles, I averaged 69.1 mph and 39.2 mpg with me, wife, our black lab and luggage (maybe 450 - 475 pounds). 

 

As far as economics on the trip, we make the trip of about 2050 miles with one night stay over (about 30.5 hours of driving time).  If I would slow down to the speed limits (about 5-7 mph slower than the normal traffic flow), I'd likely add about 5-6 hours to the trip which would require a second night stay.  I can buy a lot of fuel for $100. :)  So, slowing down in this case costs me $$$ and time. ;)

[marshtex2]

The elevation difference was about 400 feet and the lowest mpg came on the down hill part of the trip where I stayed on Eco-Cruise+ up and down hill.

 

I am not insensitive about interfering with faster traffic. I was on light to very lightly traveled I-5 and I-505, way up north, nothing like LA. A lot of cars passed me but none had to struggle along behind me. Especially I respect the big rig's need to not get trapped behind a slow poke.

Edited April 15, 2015 by marshtex2

[SPL Tech]

 

It's simple, the Cmax, and just about any other car, gets the best fuel economy at about 20 MPH. From there as speed increases, fuel consumption increases in a very predictable and logarithmic path. This data can be charted in Excel quite easily. There is no magic speed here. The fuel consumption increase that occurs as speed increases is very  predictable all the way up to the maximum speed of the vehicle. I drive at about the same speed as everyone else. I found I got about 35 MPG at 85 MPH with no wind, which is better than most cars. A truck will get about 15 MPG at that speed, a semi, 5 MPG.

 

 

Edited April 16, 2015 by SPL Tech

[Kelleytoons]

Yup, as he said.

 

But I will post one contrary opinion -- while I don't impede traffic, I also don't go as fast as some.  For me it's not only MY TIME that's more valuable than money, it's MY LIFE.  Folks often drive at unsafe speeds and "going with the flow" isn't any safer just because the flow is insane (just make sure you stay to the right and let the idiots pass you).

[scottwood2]

Good post.  I have looked at MPG a lot but I have not really broke down the cost.  Not really saving that much if you are going on long trips and need to get there. 

 

On the other side for local runs I have many times taken surface streets as apposed to freeways.  Depends on how much time I have.  Benefits are: 

 

- I get to drive the C-Max more which I love to drive.

- Increased FE which has become somewhat of a game to me. 

 

Funny thing though, I know the roads around me and the timing of the lights.  I do many times do what I need to do to time the lights.  I do have some people get upset that I am not racing to the light to slam on my brakes.  Many of these people I see on the road every day as I go to work.  I catch up to them at the light and sometime blow by them just as the light turns green.  A bunch of them in the morning have now slowed down and drive with me now.   More relaxing and we all get there at the same time anyway. 

[hybridbear]

I agree about safety being another factor. Your probability of dying in a crash increases exponentially as your speed increases. We've found 65 MPH to be a good balance between speed, time & MPG. We usually keep to 65 MPH if the speed limit is 65 MPH or higher. I'll speed up going down hills to improve efficiency, sometimes as much as a 10 MPH increase.

[ptjones]

The elevation difference was about 400 feet and the lowest mpg came on the down hill part of the trip where I stayed on Eco-Cruise+ up and down hill.

 

I am not insensitive about interfering with faster traffic. I was on light to very lightly traveled I-5 and I-505, way up north, nothing like LA. A lot of cars passed me but none had to struggle along behind me. Especially I respect the big rig's need to not get trapped behind a slow poke.

Was there any wind involved? :)

 

Paul

[Bugblndr]

Was there any wind involved? :)

 

Paul

 

Interesting you made that comment.  From October - April, every week I do the same trip at about the same time, 80 miles west going up 400 feet in elevation, then the return trip at the end of the day, 80 miles east going down 400 feet in elevation.  Almost all of that elevation change occurs on one hill.

 

In the C-Max, I set Eco Cruise at 65 MPH (speed limit is 62) and there is no traffic to speak of.  

 

Westbound uphill into prevailing winds - 37 MPG

Eastbound downhill with the wind - 46 MPG.

 

I've only had the C-Max 3 weeks but in each case the results were similar, but with a bit lower MPG which I attribute to the car being brand new and the weather being colder.

[marshtex2]

No wind of consequence.

[fbov]

That's highly unlikely.

 

There's always air movement, what are known as "prevailing winds." A google search for " prevailiing winds sacramento" yields this:

SACRAMENTO EXECUTIVE AP, CA  |   SE  SSE    S  SSW    S    S    S    S    S    S  SSE  SSE  |    S
SACRAMENTO INT'L AP, CA (KSM |  SSE  SSE    S    S    S    S    S    S    S    S   NW  SSE  |    S
SACRAMENTO-MATHER AP, CA (KM |   SE   SE   SE    S    S    S    S    S    S   SE   SE   SE  |    S
 

I didn't copy over the monthly headers, but it's clear the prevailing winds in that part of CA is Southerly.

 

I-5 and I-505 run north-south. It's highly likely that prevailing winds are affecting your data.

 

Despite a known link between ambient temperature and mileage, my 3K mile trip to Louisiana last year showed no temperature affect, but a very strong directional affect due to prevailing southwesterly winds. 33.7 MPG into the wind, 37.7MPG with a tailwind. It's as important as elevation over long trips as elevation has its limits.

 

Have fun,

Frank

[Adrian_L]

It's simple, the Cmax, and just about any other car, gets the best fuel economy at about 20 MPH. From there as speed increases, fuel consumption increases in a very predictable and logarithmic path. This data can be charted in Excel quite easily. There is no magic speed here. The fuel consumption increase that occurs as speed increases is very  predictable all the way up to the maximum speed of the vehicle. I drive at about the same speed as everyone else. I found I got about 35 MPG at 85 MPH with no wind, which is better than most cars. A truck will get about 15 MPG at that speed, a semi, 5 MPG.

 

 

 

100% correct.  But 85 mph?!   That would get you a serious fine in Canada (136 kph).  

 

I agree with the other fella that 65 seems to be a great, safe speed and keeps the blood pressure low.  And the consumption.

Edited April 17, 2015 by Adrian_L

[shinytop]

Have had my C-Max almost 11 months with a little over 7K on it.  My daily drive to work is mostly in a 45 zones, part 4 lane and part 2 lane.  I live in the the Florida panhandle so not much cold weather driving.  I almost always get over 50 MPG to and from work with my best being 65 MPG.  I know the route and where I will be able to let the battery engage.  Other than on rainy days I find the biggest factor in the mileage is timing the lights and the actions of other drivers.  Drivers pulling onto the road and forcing me to brake obviously cuts the mpg.  On the four lane I try to always drive in the right lane to not impede the people who must push the limit.  On the two lane 45 MPH sections I stay around the speed limit.  As others observed I find I often catch the speed demons at the next light.  

 

My long term mileage goes down after each highway trip.  On the interstate I usually stay around the speed limit although in heavier traffic I will speed up to 75 to keep up with the speed in the right lane.  On those trips I hover around 40 mpg.

[Automate]

But 85 mph?!   That would get you a serious fine in Canada (136 kph).  

 

Parts of Texas have an 85 mph speed limit.  http://abcnews.go.com/US/speeding-texas-85-mph-highway-opens/story?id=17549839

[plus 3 golfer]

If rural interstate speed limits were set based solely on safety, we'd likely have interstate speeds of around 60 mph maximum.  The approach I like is the 85th percentile engineering approach on rural freeways and interstates (the speed at or below which 85 percent of the free-flowing vehicles travel).   Let drivers determine the "safe speed".  :) 

 

From TXDOT: "Research has shown that speed limits set below the reasonable speed of most drivers do not significantly reduce the number of crashes on a road. In fact, crashes may increase with unreasonably low speed limits."

 

Here's a good read on speed limits that's a few years old.

[Adrian_L]

Even in Texas, God hath not decreed that thou must drivest the maximum speed posted :victory:

[HotPotato]

Yep. This spurs me onto my soapbox.

 

Speed doesn't kill: speed differential kills. If you're going 50 and someone hits you going 80, you're in much worse shape than if you're going 64 and they tap you going 65.

 

Safest bet: leaving a safe following distance, match the prevailing speed of traffic in the center lane, and be courteous trying to those trying to enter your lane from left or right. Never dwell in the passing lane, unless actively in the process of passing someone.  

 

Occasionally you'll see some jackass in the passing lane going the speed limit. This endangers the jackass and everyone else, and enrages the angry guy behind him...you know, the one tailgating and flashing his lights. Who knows why the angry guy is trying to pass--maybe he is a doctor racing to the emergency room to save a life before it's too late. Depending on the state, the highway patrol can ticket the jackass for either remaining in the passing lane or impeding the prevailing flow of traffic, regardless of whether that prevailing traffic is speeding. Those tickets are as valuable to traffic safety as speeding tickets, because...speed differential kills.

 

Stepping off the soapbox now, thank you all for your indulgence.

 

 

Yup, as he said.

 

But I will post one contrary opinion -- while I don't impede traffic, I also don't go as fast as some.  For me it's not only MY TIME that's more valuable than money, it's MY LIFE.  Folks often drive at unsafe speeds and "going with the flow" isn't any safer just because the flow is insane (just make sure you stay to the right and let the idiots pass you).

[kostby]

Even in Texas, God hath not decreed that thou must drivest the maximum speed posted :victory:

 

 

Yep. This spurs me onto my soapbox.

 

Speed doesn't kill: speed differential kills. If you're going 50 and someone hits you going 80, you're in much worse shape than if you're going 64 and they tap you going 65.

 

Safest bet: leaving a safe following distance, match the prevailing speed of traffic in the center lane, and be courteous trying to those trying to enter your lane from left or right. Never dwell in the passing lane, unless actively in the process of passing someone.  

 

Occasionally you'll see some jackass in the passing lane going the speed limit. This endangers the jackass and everyone else, and enrages the angry guy behind him...you know, the one tailgating and flashing his lights. Who knows why the angry guy is trying to pass--maybe he is a doctor racing to the emergency room to save a life before it's too late. Depending on the state, the highway patrol can ticket the jackass for either remaining in the passing lane or impeding the prevailing flow of traffic, regardless of whether that prevailing traffic is speeding. Those tickets are as valuable to traffic safety as speeding tickets, because...speed differential kills.

 

Stepping off the soapbox now, thank you all for your indulgence.

 

10-4

And that's why law enforcement officers in the heart of NASCAR country must now display the NASCAR "move over" flag (blue with diagonal orange stripe) in most states before writing you the ticket.  ;)

Or radio ahead to deploy stop sticks just up the road.

Or shoot your tires out.

Whatever gets the job done.

And doesn't get captured on their in-car camera  :camera:...

[shinytop]

Agree about not impeding traffic.  BUT, it seems when the flow of all traffic, including the slow lane, is approaching10 MPH over the speed limit the distance between cars is also narrowing which keeps one from the standard car length for every 10 MPH of speed.  

[SPL Tech]

100% correct.  But 85 mph?!   That would get you a serious fine in Canada (136 kph).  

 

I agree with the other fella that 65 seems to be a great, safe speed and keeps the blood pressure low.  And the consumption.

Isint the speed limit up there 120? So 135 in a 120 is nothing. That's like the average speed most people would drive in that speed zone anyway.

[nsteblay]

End Time Distance (mi) Duration (min) Avg MPH Average MPG 5/1/2015 18:03 33.33 80.26 24.92 51.58 5/1/2015 7:17 32.35 53.77 36.10 53.67 4/30/2015 17:29 34.56 81.64 25.40 51.9 4/30/2015 7:16 36.91 49.67 44.59 49.06 4/29/2015 21:15 32.55 40.77 47.90 49.41 4/29/2015 7:03 37.43 46.22 48.59 49.35 4/28/2015 17:26 35.06 70.79 29.72 54.71 4/28/2015 7:36 36.85 65.66 33.67 50.62 4/27/2015 18:23 37.22 50.89 43.88 49.14 4/27/2015 7:12 37.68 49.23 45.92 48.63 4/24/2015 17:20 32.73 73.73 26.64 49.01 4/24/2015 7:04 32.38 48.86 39.76 51.49 4/23/2015 17:56 32.14 68.31 28.23 50.59 4/23/2015 6:55 36.89 49.91 44.35 49.15 4/22/2015 20:17 25.99 34.15 45.66 44.65

 

 

 

Freeway driving commute to work these past couple of weeks - I use the "Automatic" OBDII scanner to get the numbers.  The freeway is often congested so my average MPH is low but when its open I go with the traffic which is often over the speed limit. The CMax is designed as a commuter car and gets better mileage at lower MPH.

 

Oops - table pasted fine but didn't render after submit.

Edited May 4, 2015 by nsteblay

[ptjones]

See if this works:

End Time Distance (mi)   Duration (min)   Avg MPH   Average MPG

5/1/2015 18:03     33.33    80.26                24.92               51.58

5/1/2015   7:17     32.35    53.77                36.10               53.67

4/30/2015 17:29   34.56    81.64                25.40               51.9

4/30/2015 7:16     36.91    49.67                44.59               49.06

4/29/2015 21:15   32.55    40.77                47.90               49.41

4/29/2015 7:03     37.43    46.22                48.59               49.35

4/28/2015 17:26   35.06    70.79                29.72               54.71

4/28/2015 7:36     36.85    65.66                33.67               50.62

4/27/2015 18:23   37.22    50.89                43.88               49.14

4/27/2015 7:12     37.68    49.23                45.92               48.63

4/24/2015 17:20   32.73    73.73                26.64               49.01

4/24/2015 7:04     32.38    48.86                39.76               51.49

4/23/2015 17:56   32.14    68.31                28.23               50.59

4/23/2015 6:55     36.89    49.91                44.35               49.15

4/22/2015 20:17   25.99    34.15                45.66               44.65

 

Good Info :)

 

Paul