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Topic: Most fuel efficient highway speed? (Read 1805 times) previous topic - next topic

Re: Most fuel efficient highway speed?

Reply #25 –
...wow, thanks for all those answers, even to stuff I didn't ask ;D  I can't drive slower than 50 mph because my transmission doesn't shift into high gear until about 48 mph and I'm sure it's most fuel efficient in high gear. I suspect 55 mph might be more fuel efficient than 60 mph on flat land, but it seems like the torque converter unlocks more often on little hills at 55 than it does at 60, which sorta loses whatever advantage there might be. A lot of fleet vehicles are governed at 60 mph now, so I presume it's the most efficient speed for a lot of those vehicles or the owners wouldn't have done it. I'm running my tires at Foretravel's recommended 90 psi or slightly higher. The previous owner experimented with higher pressures but said he didn't notice any advantage. He told me it rode a lot harder so he reduced the pressure some. When I bought the coach he had the tires at about 95 psi. I jumped to the conclusion that wind resistance was the major fuel efficiency factor and never messed with the rolling resistance. I drive with about 25-50 gallons of fresh water and empty gray and black water tanks. My cargo bays and cabinets aren't fully loaded and I'm carrying a motorcycle instead of towing a car. I suppose any reduction in weight is an improvement in fuel efficiency and hill climbing ability. Foretravel doesn't disappoint in either category. I pass every other coach going up steep hills, but they all pass me again going down the other side. Every other coach owner I've talked to says they're getting significantly less than 10 mpg. Most of them are in new Phaetons with flat noses. I even spoke to a guy with a pickup truck that barely got 10 mpg without towing a trailer the other day. Basically everyone is amazed that I get 10 mpg. Foretravel obviously knew what they were doing and optimized everything.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Most fuel efficient highway speed?

Reply #26 –
When I was in a truck repair shop last month a driver was there trying to get his engine reprogrammed to allow 70mph since the speed limit on US 59 was just raised to that point.  It took a lot of discussion between the service manager and a decision maker at the trucking firm.  The shop was finally allowed to re-program to 65mph on cruise but only 60 off cruise.  Do you think these companies are taking fuel mileage seriously?  It's something to see trucks crawling across west Texas at 60mph when the speed limit is 80.  Didn't used to be that way.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Most fuel efficient highway speed?

Reply #27 –
Sometimes it is for accident control and insurance too.  They get a better rate if they are governed.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Most fuel efficient highway speed?

Reply #28 –
I'm never bored with  any of our trips over the past several years. I believe that if I needed to get somewhere faster than the 57 mph sweet-spot I'd simply take a plane and get the "awful" drive over with. The whole trip is the trip to us and we enjoy all the things we see and enjoy the things we stop to se between point A and B. I retired and learned that the yellow means slow down rather than speed up. I learned that what was passing me by in the front and side windows was the actual reason for this lifestyle. I learned that pennies saved were, in fact, pennies earned. We only go above the sweet spot when going down hill and even then I pull on the retarded and wonder what in the world we're going so fast for.
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk

Re: Most fuel efficient highway speed?

Reply #29 –
Howdy Larry, 
  Well said, sir!!! 
 Dave A
Dave and Nancy Abel
'00 U320 36' WTFE  Build #5669
'10 Jeep Wrangler Unlimited Rubicon
Livingston, TX  SKP's Fulltiming

Re: Most fuel efficient highway speed?

Reply #30 –
They also get lower insurance rates.
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Most fuel efficient highway speed?

Reply #31 –
Quote from: John S –
Sometimes it is for accident control and insurance too.  They get a better rate if they are governed.

This confirms my point. Go faster.  Increase risk.  Going slower is not just related to saving fuel/$$$.

best, paul
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: Most fuel efficient highway speed?

Reply #32 –
Quote from: RRadio –
...wow, thanks for all those answers, even to stuff I didn't ask ;D  I can't drive slower than 50 mph because my transmission doesn't shift into high gear until about 48 mph and I'm sure it's most fuel efficient in high gear.

My 6th gear locks in at 62mph.  Then in cruise control I can bring it down to 60mph and stay in 6th in rolling hills (with 'mode' on).

But my VMS 240 CL surprised me when it showed higher mpg at 55mph in 5th gear. 

As an aside, I discovered my VMS 240 CL to be an important safety device. All the engine stats are right there in front of my eyes, changing and changing from road circumstance to another. My VMS changing and the scenery changing keep me awake...

But then, being so engrossed in RPM, torque vs speed, recent MPG, seeing if I can squeeze 0.1 mpg more out, etc, etc, is not my fault. I'm an engineer. They beat it into us ;o)

Pity Kathleen. No one ever warned her about engineers.

But then, no one ever warned me about redheads either (running and ducking...)

best, paul
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

Re: Most fuel efficient highway speed?

Reply #33 –
Quote from: amos.harrison –
Do you think these companies are taking fuel mileage seriously?
If you have a trucking company with 1000 drivers and you decrease the MPG of each truck by only 1MPG you can save millions of dollars a year, yes it is only pennies for each day for each truck but my Mom always said, "Watch the pennies, the dollars will take care of themselves.

1000 Drivers
20,000 miles per year
Total miles 20,000,000
@6MPG 3,333,333 gallons of fuel
@5MPG 4,000,000 gallons of fuel
@ $3.00 per gallon  @6MPG 9,999,999 @5MPG 12,000,000
Decrease of 1MPG per driver saves a little over $2,000,000 in fuel alone

When I was a company driver, the company rewarded folks for low IDLE times just to save PENNIES. Their trucks were also governed at 60MPH. Schneider at that time was governed at 55MPH. You can adjust schedules to compensate for longer driving times, but you cannot recover the fuel that is burnt needlessly.

I know some folks say they "get sleepy" when they drive 55 or 60 MPH. If that's the case stop and smell the roses, let the DW have a turn at the wheel. That's what we do, we also avoid interstates whenever we can. Got into the fulltiming lifestyle to see this country, not watch go by through my windshield.

Roland
 
1993 U280 4341
2010 Jeep Liberty
The Pied Pipers

Re: Most fuel efficient highway speed?

Reply #34 –
A dollar a day each truck, for a fleet of 15,000 tractors sure becomes an interesting number each day,  Think large fleets such as Schneider, UPS, FedX etc.
Why the bean counters & insurance become a force to deal with.

Re: Most fuel efficient highway speed?

Reply #35 –
Quote from: Paul Smith –
This confirms my point. Go faster.  Increase risk.  Going slower is not just related to saving fuel/$$$.

best, paul
Thats funny!!!  I quit driving over the road as a independent in 1983 when I took a regional delivery job for a union outfit hauling bulk petroleum products.  One of they things they told me was "this company runs legal"!  They told me "we don't speed"!!  Also told me "we don't lie on our log books" !!!  And then they also said "you don't need to hurry"!!!  I thought they were nuts, but come to find out, that was how they operated.  I had a heck of a time slowing down
1994 U225
build #4514

Re: Most fuel efficient highway speed?

Reply #36 –
Interesting, that no one mentioned the optimum operating RPM (found in your engine manual) for a given engine. This is the point where max torque and horse power meet. Not all engine engines do well at lower RPM's (you 2 stroke guys that know well) My ISC is like 1650-1800 RPM fuel consumption aside the engine runs cooler and better oil pressure. By useing the manual shift for the transmission when on secondary roads, city traffic, it helps minimize low RPM's and excessive shifting.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Most fuel efficient highway speed?

Reply #37 –
             The reason I bought my Foretravel in the first place  is the comfort factor ! All the little things that enter into that include the speed that I drive . I do tune into the MPG , but that is not my driving force .I see that RPM is what shows the best or worst MPG to a point then MPH also enters as pushing or pulling air has it's effect .Back to comfort , yes that is my thing . The road , traffic and general road conditions are what is my comfort thing . I have no problem with 55 MPH as well as 75 or so MPH .Not a bean counter nor a complete dumb butt , so MPG is important ,but driving comfort and feeling good going down the road is why I have a coach in the first place . I know this is a different strokes for different folks thing .      Brad Metzger
Brad Metzger
2010 Phenix 45'

Re: Most fuel efficient highway speed?

Reply #38 –
Agree with Brad...This is a very individual pursuit.  MPG has always been a "thing" with me...must be the engineer thing coming out...it's just ingrained in my mentality to seek the most efficiency from anything.  Engines lend themselves easily to this king of thought.  It really is not that critical a statistic insofar as motorcoach driving goes.  Let's face it, we just don't drive that many miles to make a world of difference.

e.g.  I typically drive the coach 10,000 miles per year; and some years only 5,000 miles.  The variance in mpg I've observed over 10 years is between 7.5 mpg (Power setting on Allison. towing and in hilly high altitudes) and 9.0 mpg (using MODE on Allison).  At $4.00 per gals. this is a total cost difference of $915 for the entire year/season if driving 10,000 miles, and only if I were to change driving habits for an entire year.  Granted, to some the $900 difference is important.  And if you drive 40,000 miles per year, then it does begin to be a few more bucks than even I am willing to "burn"...no pun intended... :o
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Most fuel efficient highway speed?

Reply #39 –
I look at mpg more as a "am I driving right" and "is everything running as it should" more than "Can I save a few buck this leg of the trip". Otherwise my RV would be a TDI Jetta or something similar.
Jay
1989 U280 SE, 36', 3208T Cat, build 3292

Re: Most fuel efficient highway speed?

Reply #40 –
Quote from: twobus –
I look at mpg more as a "am I driving right" and "is everything running as it should" more than "Can I save a few buck this leg of the trip". Otherwise my RV would be a TDI Jetta or something similar.

I don't know about that Jay???  As I remember, the guys who were getting the really high mpg with their TDIs were getting lots of oily crap coming through their EGRs and plugging up their intakes super bad.  But if you ran the heck out of the 1.9 ALH diesel, it will not plug up.
1994 U225
build #4514