What's your time worth? Fuel economy vs speed.
 

I thought I would post this here since it doesn't really fit elsewhere but I like punching numbers and think this might be interesting to some of you here.

I got a scangage on Friday and after some initial tinkering decided to see what kind of difference cruising speed really has on fuel economy.

Before the gage I would mostly cruise at 105km/h feeling it was a good compromise between getting where I am going in good time and saving fuel.

I reset the trip meter approximately every 100km on the open highway alternating between 100, 105 and 110km/h

for the 100km/h runs I got 10.1, 11.7, 11.2 and 10.4l/100km - average 10.9 l/100km
for the 105km/h runs I got 12.7, 11.3, 11.8 and 12.3 l/100km - average 12.0 l/100km
for the 110km/h runs I got 13.2, 11.9, 12.5, and 11.6 l/100km - average 12.3 l/100km


Using $20/hr and $1.25/l the net cost of going 105km/h over 100km/h for 100km was 52¢
Using the same numbers I was surprised to find that going 110km/h over 100km was basically a wash at -.5¢

I always figured going faster would have diminishing returns with fuel burnt trumping time saved. This is definitely not definitive in any way but interesting none the less. I am going to have to mix in a few hundred klicks of going 115 next time I go home and see how that works out.

The data was gathered on a trip from work to home for the weekend then up to La Ronge and back to work today. It is not a good controlled experiment but "psudo-random" I didn't use anything from the first 30km of driving or when I got close to a city where there was other traffic. Datums were from 90km to 125km long but mostly right around 100km. Roads were varied but I was surprised by the variance in readings despite the fairly long intervals. (I thought things would average out since there hasn’t been much wind and little elevation change.)


Anyway thought it was interesting. has anyone else here thought about having a "slow speed" and a "fast speed"? looks like my 105km/h compromise isn't really such a good idea after all.

Being retired I have plenty time. If you have the opportunity to turn your time saved into income then time becomes a factor. Most people employed earn a wage for the hours worked. After all of the payroll deductions and expenses you get a fraction of your gross wages. After that what comes out of your pocket is gone forever unless it is paying for an asset. Understanding this means you are paying much more for gas than what you spend, because you have to earn significantly more to have the amount you pay for gas left over after deductions.

I like to keep as much of my money as possible. Getting 45-75 MPG out of my vehicles means money in my pocket.

At $3.50 a gallon 100k miles in a 10 MPG FSP is $35,000.
At 50 MPG it's $7000.

That's $28,000 in my pocket in 100k miles.

Put that in the bank for 5 decades or another better investment. Lets say I bought gold with the gas money I saved for 5 decades at 15k miles a year. Now you are talking about some serious wealth.

regards
Mech

Thanks for taking the time to do that.:)

My daily commute includes 20km of 110kph motorway.
Driving that leg at 100, or even 90kph only adds a few minutes to my travel time and aids my fuel consumption.

If I'm on an extended motorway trip (hundreds of kilometres), that extra time can become a problem (worse if I've got passengers) and I usually drive closer to 110kph (averaged between uphill and down).
The increased fuel economy from no stop/start driving more than compensates for the lower fuel economy of the higher speed.

I can putt along and my time has not value, when others are in the car the fuel saved isn't worth it. PSL + a few atleast until they fall asleep.

I fail to see how driving faster is saving the average person money. When I am driving I am not working therefore I am not making any money. I am, however, spending money on fuel. If i show up to work early i do not get paid more since i am paid a salary. If I choose to drive 60mph I can get approx. 61mpg. If I drive 75mph I may only get 50mpg and I only save 10minutes over my 49mile one way commute. I never understood the whole "my time is worth $$" when you are not actually acrueing hours in your profession. If your earnings are limited by the hours in a day then speeding may make sense but not many professions have this problem.

Depends on the trip.

I recently drove back from San Diego to D.C. I averaged approx 70 mph, maybe a bit higher. The added time by reducing speed to 50mph (15 hours) would've cost me an extra day minimum, meaning another hotel stay ($50), 6 more meals ($30), and another day of pay ($160 @ the $20/hr listed above for 8 hours) = approx $240. I make more than $20 an hour, so my cost would've been much higher.

Gas for the trip was only $340... to save $240, we would've needed to get 104mpg @ 50mph. To save enough to offset the cost for me, the car would've needed to get ~2600mpg - enough to make the gas essentially free.

If I could have averaged 80 or 90 without any safety risks or risk of a ticket, I would have.


On a daily basis, the same does not apply (I am salary). I'm not patient enough to do serious hypermiling (and I believe many practices are inconsiderate to other drivers), but I do coast when no-one is around and generally drive with moderate attention to fuel efficiency. But, my time still has some value, so I drive accordingly. I don't race everywhere, but I'm not going to drive 50mph on the interstate either.

Its the same reason some people pay others to work on their car, mow their lawn, repair their house, etc. You only have so much personal time, and sometimes you want to spend it doing something other than driving A to B.

What is Time?
What is Value?
What is Money?
What is...?

What do most of us do with the time we have "saved" by getting to our destination faster/sooner? I suspect that the time is wasted in some other manner...

We can not control time, we can control fuel consumption.

Probably that saved time will be spent in ecomodder forum :P
Or if you are not hypermiler, then it will be spent by drinking beer and watching something pointless on TV.

Yes, but who is to argue this is wasted time? I enjoy surfing ecomodder, watching Breaking Bad, cooking my dinner, working on my cars, weightlifting, mountain biking, etc. much more than I enjoy my commute. Leisure time != wasted time.

Anyone who is concerned about time=money enough to speed better have a really, really short commute or they are barking up the wrong tree!

I have a 63 mile one way commute to work daily. I timed the trip and gauged tank to tank fuel economy. I discovered that doing 65 mph (10 over) only saved me seven minutes of drive time, but cost me 6 mpg. I put along whether anyone is in the vehicle with me or not. I am salary and prefer to enjoy the ride. BTW, has anyone ever considered what speeding would do if you got a ticket? Talk about blowing money. I'll enjoy the roses instead of being in a rush.

Commutes costing you money? Simple answer, really... wake up earlier... :D

Lol, I do that already. I have learned to smile and wave to those who lean out of the car cussing you out for doing 55 in a 65. I just give myself plenty of time, and like I said, enjoy the ride. :turtle:

Best money I made was when I glued rocks to the foundation of my house. Since I was living there (built it myself) I had no commute, just walk out the garage door and mix up some mortar and slap it on the rock, then stick the rock on the cinderblock wall. Took me two months to cover the almost 2000 square feet of wall. In some spots it is 12 feet tall. Used a big mortar bag to squirt extra mortar into the gaps and smoothed it out with my finger. Break up rocks for pieces to fill the gaps.

Best quote to have someone else do it was $18,000. Cost me $1400 and my time. Not a single one has fallen off the foundation in almost 8 years. :thumbup:

Probably spelled mortar wrong. :eek:

regards
Mech

Depends on the mortar you are referring to.

I have been 2 miles or less from work for the last 9 years.
It has saved me thousands of hours of driving.

You poor thing. What do you do to get your hypermiling fix? :D

I enjoy my commute. It's fun trying to best my last tank. With the 2012 Prius it gives you a trip summary every time you power off the car. This lets me know how well I did for that particular trip. It looks like this.

So I can check my uphill morning commute.
http://fatalfoo.com/pics/Cars/Prius/...e%20uphill.jpg

Then check my downhill evening commute.
http://fatalfoo.com/pics/Cars/Prius/...ee/85.4mpg.jpg

Without messing with my trip meters for that tank.

Before I retired, my time was worth $60/hr. I could have driven (an 80 mile RT), at a round trip time of about 1.7 hrs/day. Instead, I took bus, BART, & bus for a total daily commute time of ~4 hours. Driving speed wouldn't have mattered much, as rush hour congestion slowed everyone to an average speed of 60 mph on the morning commute, and 40 mph on the afternoon commute.

Rather than drive a SOV, I took public transportation. I read my newspapers, magazines, and books, and did the daily Sudoku and crossword puzzles - luxuries I obviously couldn't do safely while commuting. Driving would have actually left me with less available daily quality time to do my reading.

I personally love my commute for right now. It gives me "windshield time with God". I have spent the last few weeks laid up from surgery and have not been driving, and it did save a lot of money. But I enjoy the relaxing country drive.

I love taking the bus or train...l plenty of time to read... write articles on my netbook or sleep.

On my 31 mile / 50 km (one way) commute, it seems to make bugger all difference wether I drive 85 kph or (try to) drive 120 kph.
I still leave home at the same time as years ago, I still arrive at work around the same time.
Going back home, it's the same.
My commuting time is obviously far more influenced by things happening on the road, than by the speed I drive.

On long trips, going faster can cut hours from the travelling time, which can be well worth it.

I said that time will be spent, not wasted. Spent or wasted - thats your decision.
Spent time != wasted time

Arguing over time is a waste of time !

Vanity of vanities; all is vanity.

Time is always wasted.

That said, each of us has different ways we prefer to waste it. Some enjoy wasting it on the road, others in front of the TV, still others might prefer exercise.

If you are not driving in a wasteful manner, you should not feel guilty about when you drive, and about that you actually enjoy your time behind the wheel.

I understand the long trip; extra day if I go slower thought pattern, but for myself; it would be inexpensive campgrounds, or even less then that, instead of a motel/hotel.

This shows how different we all are, the values we were raised with: what is considered NORMAL to us!

I crave long road trips 5 states away at 50mph. Would enjoy going 70mph IF I had the wearwithall to afford a vehicle that could give me the early 60's mpg. my current ride gives me at 50mph. I do ALL I can to help faster traffic get by.

For those of us who can't afford a new car every 6 years or so, or don't like that new of a vehicle: some of us don't turn off the engine at every stoplight, we don't gas it up to 80% potential going up steep hills, and mountains....BECAUSE: we are driving vehicles with over 200,000 miles, or income is low, or non existant, so we want our rides to LAST basically forever, so we minimize any potential extra electrical wear, and tear, and keep the rpm's as low as possible because we want that engine to last forever!

Not exactly the dream situation, but the hard facts some of us have to live with.

It's my knowing the potential of harder times, that led me to wanting a 62.9 mpg ride. If I was fat, and happy $$ wise; conserving would probably never crossed my mind.

My cloud has its 62.9mpg lining, and I'm very proud of that. Regular was $4.17.9 around here just a couple of weeks ago. We know more of that, and more will return.

Just saying each situation is different. Its so easy to look down our nose at someone who doesn't think just like us club.

Of course the problem with that is the AFAIK untested assumption that those things do in fact cause significant extra wear.

The fallacy of the busy trap. It's nice to know someone recognizes what's going on in American society.

I know if I ask ten friends to go on the trip of a lifetime next month, 9 of 10 will say no, because they have to do laundry, or something similar. I've lived my life vowing I won't end up like them! So I've been to all the continents and oceans except Antarctica and the Great Southern Ocean, and guess where I'm going next?

It may just be my observation and I could be wrong, but it seems that the faster people travel on a regular basis, tends to aid them in being less patient.

When I think of people buzzing around because their time is "too short", I wonder how people who had only a horse/buggy for transportation, felt about "time" 100 years ago?

Jim.

Generally I would consider myself one of the slower drivers but in this group I could probably be lumped in with "faster people" and yup I travel on a regular basis. I am not sure what you are saying about patience, could you clarify?

I have 700km to drive tomorrow and 600km on thursday. Will I be speeding? yah sometimes.

Depending how the gravel is tomorrow I might be going 110-115 on the paved sections since I only have 8 hours to do the trip before someone else is sitting at the compound enduring unpaid overtime until I get back. Burning an extra $20 of gas would be worth not having a co-worker have to wait a whole hour for my return, keeping good work relations and also finishing on time.

On thursday I have no such constraints so normally I would be going slower but I want to test out how going 115km/h compares to 100, 105, and 110 for fuel efficiency in relation to the first post on this thread. I will be alternating my speed.


I bet you if people had places to be 100 years ago they pushed their horses a little bit harder to get there in a bit faster, no different than today.

I didn't get any more info on tuesday since I took the work truck but got some more interesting numbers yesterday on the drive home.

I was listening to an audio-book so decided to use the chapter lengths as my intervals. This time I recorded distances and did not throw out the "short" runs interrupted by towns or construction. I still didn't record anything from the first half hour or when there was other traffic on the road affecting my speed. Cruise control and max A/C.

Here is the raw data recorded from my scangage on each leg:
km/h (average) - l/100km - km traveled

100 12.6 58
114 13.6 92
105 13.3 64
110 11.3 59
100 10.6 57
114 13.8 72
104 11.8 48
110 12.1 30

Combining the new numbers with the old ones I made a bubble chart giving the old numbers a 50km weighting (since I was not so careful about conditions on those numbers)

http://i860.photobucket.com/albums/a...cencygraph.png

115 is obviously NOT an efficient speed, but the flat trend between 105 and 110 is interesting.

My o6 corolla gets 55-65 mpg cruising at 55 mph At 65 mph it's down to 32-40 At 75 I get high 20s. Love my scangauge.

Why I want to test is constant speed in different gears, to see why the drastic change. Is it engine efficiency that suffers, aerodynamics or rolling resistance. I will cruise and check differen speeds in different gears, what I wish I had was a 10-15% larger tire I could put on to lower engine speed a highway speed

Probably Air Resistance
 

Probably Air Resistance...drag increases with velocity squared.
Power to overcome air resistance increases with velocity cubed.


Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW).

en.wikipedia.org/wiki/Drag_(physics)

You know... wink. If people would just walk slower and forget about running, doing hard work or climbing stairs they would use less calories and as a result they could eat less and wasting less food energy possibly saving the planet.

Sorry I can't help myself at times. You see for the most part we are preaching to the choir. Those of us who care about good mileage and living a more frugal lifestyle will only have a limited effect until the technology is widely adopted by the market.

Having 50+ MPG cars can become very addicting and having large instantaneous MPG readouts sure can make a difference how hard we mash the pedal.

After having visited many central and south American countries, one thing that surprises me is the lack of attention to driving habits. In these less wealthy countries where fuel costs more than the US, they tend to drive small and fuel efficient vehicles, but neglect to drive efficiently themselves. The throttle and brakes are used as on/off switches, with no coasting between.

I would think the heart of ecomodding and hypermiling would lay with those most in need of the benefits.

I've never yet gotten a ticket for driving "too slow" instead of driving "too fast"...which awards points for "cost effectiveness" to slower driving rather than faster driving.

Private owners maybe not... but some public utility drivers here have been practicing hypermiling since the 70's.

I've watched drivers here coast up to passenger stops with the engine off, and wait for passengers that way. Old-school diesel drivers also pulse-and-glide on the highway. I never understood how those guys drove until I started studying fuel efficiency.

Newer for-hire drivers don't do the same thing. And young drivers don't give a crap. They like going fast. But the old guys, the ones who paid for their own trucks and have to scrounge up money just to buy fuel, they get it.

Time is money. How you value your time may be based on labor rates or some other alternative costs. The real analysis comes into play when comparing modes of transportation. Do I drive my car, ride a motorcycle, take public transportation, ride a bicycle, or walk? One retired executive doing many speaking engagements around the country found that a twin engine aircraft was the most economical form of travel given the value of his time. A streamlined bicycle is the most efficient energy wise but may not be fast enough for a trip more than 25 miles. A car pool of four people is more efficient than a motorcycle if trip time is the same. Buses are very efficient but not at all convenient most places. When possible I use a bus and take my bike on with me to solo commute.

Time definitely is money. Simple driving style changes saved me over a gallon a day- every week that was more than a gas can that I didn't have to buy. Every three weeks I saved an entire tankful. How much time did I spend? My UG showed an average speed of 57.5 the one time I checked it. Not too shabby when you consider the highest PSL in my area is 55 and I spend a lot of time on lower speed roads.

Hypermiling helped me direct a whole lot of money to places other than commuting. I love it!

Go read the Foxfire books and have some insight; In the second one an old man commented something quite similar to this: "People back then would talk with you all day if you stopped them while they had a horse and buggy, But now people with cars won't so much as talk for a minute! They're rushing, But where are they rushing to?"

Yep, TIME IS MONEY.

Ben Franklin knew it and said it. But what could a centuries-old fuddy-duddy like him possibly know? He was never a president, but unlike all the others who were presidents, (with the exception of Alexander Hamilton) his face is on the largest currency note we have.

Some folks have more time on their hands than they know what to do with. That's one perspective. Not everyone is retired or out of work. Others are busy being productive and never seem to have enough time.

Sometimes I drive fast, and sometimes I drive slow. It depends on the situation, whether it is economically advantageous or not.

But every time old Ben shows up in my wallet, I smile. :D