Some simple math regarding fuel economy

Go hit a greasy spoon at some dingy truck stop with this information, no one will care.

You're trying to make a point to guys who made up their minds about the angle of that fuel pedal a good long while ago.

Seriously, if you try to put this sort of thing in a sensible manner towards a good number of truckers that don't care how fast they go in respects to their fuel economy; they will simply shrug you off.
This is mainly due to the fact that the people who bought/leased their trucks, and had any common sense, know not to keep the pedal to the metal 24/7.

 

Good post flightwatch.

 

But your whole set of calculations is based on "assume a .4mpg difference", but what if the difference is much smaller, which at those 2 speeds you chose I think would be.
The other critical factor is how the truck is spec'd, and what speed/engine rpm is the sweet/efficient spot. Some of the newer combinations that have the low number rears, and designed to be very low rpm at 65, if you slowed down to do the speed limit in Commiefornia, and Oregon, you might have to run in a lower and less efficient gear.

 

I totaly agree with your math.
I am a Canadian trucker of twenty four years.

Slowing down decreases the rpm,and wind resistance.
My brother also drives for a living,in fact he owns a small company.About five years agoe we talked about this.
Keep in mind,we canadians now live under the rules of kilometers per hour,so 100 km is 62mph and 110 is 68mph.Either way,be it km or miles per hour its all the same.

Ive been hauling for twenty four years.Been a company driver,lease operator,owner op as well.When i was hauling state side up to 2003 as a (uninformed) o/o i seen the cost of fuel rising at the pumps.I was running a 1998 Eagle with a 60 series engine,18 speed transmission.

Since i gained enough know how,i only run company trucks that provide me with hourly pay and a benifit pkg.Only run water truck and gravel.( just a little interjection)
But anyway,the company i work for is tops,they provide me with new equipment and excellent pay,benifits,treatment.So as a driver i want to return the respect they deserve.
How can i do this ? Do the math on this.
We are currently doing a haul of 13.5 hours,hauling contaminated soil.I run a truck and pup with a 475 cat/18 speed tran.All the other trucks have an ISX Cummins/18 Speed .The company provides fuel cards.So i asked a few drivers over the past couple weeks how many litres of fuel they were burning per day.It was about the same as mine.So what i did was started shifting at 1300 instead of 1500 and ran at 62mph rather than 70mph. I arrive 30 mins later than the other trucks to home base,at a cost of 14cdn dollars to the company,but ive burnt 12 % less fuel at a savings of 43.00 dollars .
X-30 per month thats 1290.00

 

Driver B went 30 extra miles at $1.5 earned $45 bucks minus $38 in extra fuel came out $7 bucks ahead for his effort.

 

Any way you slice it, an O/O could make a very nice truck payment by considering moving down from cruising at 66 mph+. Prior to my taking my current job as a company driver with a governed truck I codrove on my brother's KW T2000 with a governor set at 75 mph. As a reality check several months ago I outlined our experiences setting the cruise control at 70-71 mph and received some very good feedback from forum members that got me to experimenting with lowering cruising speed during my shifts and disengaging cruise control on rolling terrain (like I-44 between OKC and St. Louis) with some pretty dramatic results. The I-44 experiment results (with max loads):

Cruise control @ 70 mph with max throttle pulling the hills = 4.0 mpg
No cruise control with target speed on level ground of 61 mph and feathering the throttle and downshifting on climbs to keep boost below 50% = 6.895 mpg

Note that with the truck governed at 75 mph I was able to gain much more speed on downhills than on a governed company truck, using that momentum to get partway up most hills and feathering the throttle to top out between 40-60 mph. With company speed policies that penalize a trucker for going over 67 mph that would make it impossible to really replicate my experiment in a company truck.

Bottom line is that with appropriate use of the throttle (ie. install a boost gauge and keep it below 50% boost) and slower speed there can be some real income benefits for an O/O.

 

actually. NO he can't.

the op was inspred to write his thread. so here's my inspiration to totally contradict his inspiration.

#1. the savings in fuel ISN'T what's been posted. cuz i don't get any better by going 3 miles slower.

#2. by going slower, you drive less miles. less miles means less freight. so whatever money I MAY SAVE in fuel. gets lost in revenue which far exceeds the savings in fuel.

#3. less stress. i spend more time sleeping then driving. slower makes me tired. needless to say i HATE driving the 3 western states.

#4. most my running is in the mountains. that pretty much kills your time right there and whatever fuel savings you think may happen.

i bought one of them scangauges. it shows real time your fuel average. and i've found my best economy so far to be in 12th gear running close to 1600 rpms. at 65. empty it's in 13th gear at 68. 1400 rpms.

NOW, on that note. last weekend i did a trip from gwinner nd to denver co. over the weekend. i did the 55 mph thing. that's a WHOLE 10 miles slower. all i got was a measly POINT THREE gain. and it was mostly flat.

now here's the really fun part. i got on the 90 in south dakota. engine light came on and truck derated. turbo just flat out quit. out in the middle of NOWHERE. i shut the truck down. fired it back up. and was able to drive again. made it to north platte with engine light on. by the time i got there the dpf light came on. hit a truckstop. but it wouldn't regen. parked it till morning. fired up truck. no engine light but dpf light still on. NOW i can regen the truck.

i made my delivery into denver doing 65 with no more light. went to albu then tucson and phoenix. then reno and home. took truck to shop and spent $500 to find out nothing's wrong.

i haven't had this truck very long so it's a good thing i found that out BEFORE going into oregon and cali. cuz apparently this truck don't like doing 55. shops recommendation was to not drive that slow cuz it's probably clogging the dpf. by going faster. i'm baking and cleaning the dpf.

so you see. slower isn't saving money. it's COSTING money. in repairs and lost revenue.

out here in the mountains. the slower you go. the less momentum you have for the hills. which means it takes you longer to climb them hills. which means your burning more fuel holding that pedal to the ground for longer time frames. the faster you climb the hill the less time you spending holding the throttle down.

while the OP statement may be true. the numbers are on the very high side. and there's a lot more factors involved to saving fuel then just simply slowing down. (flat land vs. hills. slow vs. fast. light vs. heavy. brand of oil, tire pressure, properly function turbo and clean air filter)

for my truck. going slower doesn't really save me in fuel. but a lighter load does. and it's certainly not worth pulling over to regen the truck.
in other words. slower means lost revenue, and DOWNTIME for even greater loss in loads. PLUS, a kind donation to the shop to find nothing is wrong.

i'll stick with 65+. thank you very muich. and watch my wallet grow. without a check engine light.

 

No argument that speed kills mpg!
Consider this on the other hand... I pull for a barn just big enough to cover a large department store's DC w/ very strict delivery schedule. For example a dedicated route: Chicago IL to Dayton OH runs approx 650 miles, pays the truck $1,000, the driver earns $260 @ .40 / mile. and takes every bit of 14hrs for driving/ load/unload.

Truck / Driver A @ 62mph cannot complete his run (short 31 miles / day) until Friday which he can no longer meet his delivery times.
Truck gross @ 4 days = $4,000
Fuel @ 90.3 gal/day = 361.2 gal * $4.00 = $1444.80
Driver gross = $1040.00
Truck net income for the week = $1515.20 (without idle)

Truck / Driver B @ 65mph can complete 5 day work week.
Truck gross = $5,000
Fuel @ 95.6 gal/day = 478gal * $4 = $1,912.00
Driver gross = $1,300
Truck net = $1,788

1yr @ 50 weeks:
Truck driver A = $52,000 gross income
Truck A = $75,760 net income

Truck driver B = $65,000 gross
Truck B = $89,400 net

Even if driver A was as concerned about fuel savings as the owner, you can add the cost of 8hrs idle * 60 days of temperature extremes say another $1000 in fuel and I'm trying to be very conservative.

Driver A has wife Bi#@hing why don't you work 5 days like normal people, and how we gonna pay our bills!! <--- He is now working for Company B, and you have to pay for orientation, background checks, drug test etc. for new driver. Don't forget you also needed to pay a broker to get the fifth day covered.
Driver B is making $13,000 more / yr, and home every night = Happy Driver, and Happy Customer!... plus you can put him in a day cab.

For large fleets with drivers coming on duty every 30 mins not more than 20 miles away it makes sense to limit like Prime! (I know I pulled those number out my arse... but you know what I mean.)
For small barns, O/ops, lease, it can make sense to leave the trucking to the driver's best discretion.

For those reasons I will never work for large fleets! It takes a more common sense approach to run a small barn, rather than a general rule for every truck of a mega fleet.

 

cross country trip = 2500 miles. Assuming your 3 MPH / 0.4 MPG difference, it saves the fuel efficient driver $82 in fuel, but the additional 1.8 hours behind the wheel that the fuel efficient driver is required to put in costs him $54 (assuming his time is worth $30/Hr). So for $28 I'm going to drive 65 and not sweat the details. To my way of thinking, every minute you're driving with a truck or automobile beside you (passing you), and just being out there on the highway in and of itself as opposed to safely parked, is 1 minute closer you are to a serious incident.

It's not ALL about the money and the dollars. If you want to talk about the difference between 62 and 72 MPH (legally) driving out west and across the south and southwest, and the extra 3-4 hours/week that can buy to be with wife and kids, we can do that, too. If you life revolves around the money, then drive slower, but if a driver wants to drive legally, save a little time and consider the cost offsets to be a push, that's his business and that's his prerogative.