..is 15mpg REALLY possible?? .... really?

[MisterT]

I've heard folks discussing diesel MPG numbers, and several have even mentioned that dealers(or salespeople) will mention very high numbers, though we typically share this from a negative viewpoint as we don't necessarily believe 'them'...after all, they are biased, right?


well, maybe...

but today I started a 228 mile drive, starting in the mountains, hills, down thru the middle of Atlanta, and further south to $1.19 diesel in Byron, GA...

I'll post a pic of my numbers.... 14.8 mpg.

here's the other details: iSB6.7L 300hp Allison 2100

- typical RPM of 17.5 to 18
- fuel... started with a little more than 1/2 tank
- water... 1/3 tank
- folks aboard...1, plus 1 doggie
- overall coach weight, with Solar, Kyak, and cargo carrier at rear...25,450
- tire psi... 90 fronts, 95 rears
- average drive speed, on interstates... 58.... varied from 55 to 62 otherwise
- stops: 2 at a total of 30 minutes, with engine running
- no vehicle AC or Heat needed
- inverter running Fridge, WaterHeater, Computer charger
- weather: rain during first 100 miles, slight headwind, temps 75-80


by the way - straight by the new Braves stadium as game just started, and thru Atlanta with no issues, only slight slowdown several times... a Sunday of course : ) I575/I75 the whole way...

yep, it's possible... maybe you might not drive this 'slow' most times, maybe you are a heavier coach, and other differences might inhibit it, but maybe, just maybe...

[WILDEBILL308]

Well it is possible but I think it is a little optimistic. Do you need DEF? I do my milage the old fashion way. fill it up to the bottom of the fill neck(in view) and repeat. I feel at least 5 fill ups are needed to get any kind of average. This evens out road condition wind weather and the driver.
You are right every coach is different. Hope your milage continues. However I would be happy if it was 12.0 mpg.
Bill

[Stiltner]

I'm impressed! Both by your MPG and what you paid for diesel T! You da man!

[MisterT]

I only post this to give us all hope and understanding of what's capable... now, me, for instance, I might be more concerned about fuel mileage, than, say, some of the larger heavier coach owners with 450-600hp who might not readily 'believe' these numbers... it's not to boast, but to say what a newer Post-DEF Cummins compact diesel(weight/length) is capable of - if I owned a KingAire, though, I probably wouldn't be reading this post.

It's not everyday you're going to see these numbers, we certainly didn't while fighting a headwind going west thru Kansas last year - that was more in the 9's. But when folks like us have discussions about MPG, it's hard to really know what the 'benchmark' is to how you confirm this, such as weather/wind conditions, mountains vs flats, east vs west, interstates vs country roads vs metro traffic - not to mention speed, acceleration, braking, exhaust/jake brake usage, usage of AC and Heater, running generator, etc. etc.,...

but, it IS possible, just maybe not always as frequently PROBABLE as we'd like : )

[MisterT]

by the way, as for the fuel $1.19 number...

many of us also respond to posts about how to find the best stations for fuel, the easiest entry and exit, the lowest cost, etc... I only mentioned the fuel cost because an exit before this was a brand new LOVES, with a brand new exit off S I75, and was happily promoting their Diesel $1.75 price! Blinking lights and all! very appealing, maybe.

if you like truck stops, go for it. I like lower prices, so an exit later, at a 'regular' fuel station, still right off I75, the price was only $1.19. Some may say that the price is not as 'important' as maneuvering thru the pumps, but if you paid $175,000.00 for a coach that someone a mile away only paid $119,000.00 for, most of us would truthfully be *****isssed****!!!!
...maybe that's a stretch in this conversation, but everyone of us has a 'point' at which we make decisions based on monetary differences in price. For some, it's a much bigger price difference before the effort is worth it, and for some it's much lower... yes, if I needed to drive 20 miles out of the way for a lower price, then I'd most certainly have to 'recalculate' the effectiveness of the price difference, for sure.

Like some others, I use GasBuddy, or a similar fuel app. It's simple, it just shows you the differences in prices from one station to another, from one exit to another, or from one area of the state to another. If you use it, you can 'save' money. If you don't, you might still save, but it might be more about saving your time, or effort, if that's what more important.

I'll admit, though, no fuel app is every always totally perfect and accurate. You take a risk if you choose a station that is radically lower than others in a similar area, it might be incorrect, or may have changed before you arrive, or might be exactly right!
This SHELL station price was also for either cash OR credit... now that's a little unusual since I see many 'low' diesel prices as CASH ONLY.

[Robf]

Great post Mr T !!! I have always had diesel pickup trucks and I believe the sweet spot is below 2k rpm for best milage.... which seems to be right where you are. Yes I drove a little slower than others...... BTW how do we rest the milage calculator ? if to compliated to explain no problem, I can always pull out the manual.

[MisterT]

the mileage reset, and any of the other values, is to use the 4-way controller...

- push the 4-way DOWN to find the value you want to reset
- push the 4-way LEFT one time
... the information screen will now tell you to:
- push RIGHT and hold for Three Seconds to reset the value

[parks0412]

The date and time are incorrect on my dash. When I try to reset them, it tells me it's a factory setting and cannot be reset. Does anyone have a solution?

[Stiltner]

Yes. Leave the toggle switch alone until nothing is highlighted. once that is accomplished, then toggle left, then select setup, select set date and time. it gets a little getting use too.

[Vettesniper]

If you only paid $1.19 a gallon for diesel fuel at the Shell off of I-75 in Byron, Georgia then you should have filled up a tanker truck not a motorhome! It apparently has doubled in price since then...[emoji848]


Screen shot taken from Gas Buddy App on 5/23/2017 at 9:45pm

[MisterT]

yes, my bad, typo, $2.19 was the price
vs the new Loves at $2.75