"Actually, no. The "55 mph saves fuel" mantra was started in the 70's"
Oh for crying out loud, this is not that difficult to grasp.
Actually the answer is... you cannot change physics. You will use less fuel at 55 than 60, 65, 70 etc... everything else being equal. This is not refutable, try as you might.
You don't "get something for nothing." You want to go faster? You will need to push through more air. I don't care WHAT your aerodynamics are. I don't care what OD transmission you have. Pushing through air faster requires more energy. Not a lot? Who defines that? I am simply stating a fact that cannot be "white washed." Physical laws of nature dictate these parameters... don't try and mislead people into thinking that they don't have to change habits to save energy.
Good for you "pacificnw", you get it! Eventually, even the slower minds will too. Energy used is energy used and has nothing to do with denial lip service. It isn't IF we want to conserve. It's that we WILL conserve and we/all must find the fastest and most effective ways NOW before the coming mandates do and will change/ruin our lives as we now know them today. We, the American people, would have no problems in cutting our energy consumption by over 25% tomorrow if we barely tried. Replace incandescent bulbs with fluorescent, LED, etc. Turn off lights, TV's, appliances, etc, when leaving a room. Slowing of our highway driving speed and combining trips while using our more fuel efficient vehicle. Caulking, sealing, adding insulation, 3 layer windows w/one tinted, not wasting heated water, etc. Very short refrigerator door openings and full load clothes washing and drying etc. There are unlimited measures we can take that won't have any effect on our RV'ing or home daily lives. Even a 25% reduction is HUGE and will play a gigantic role in the market economy laws of "supply and demand". You want more and the market forces can charge more because of the demand. Very simple economics 101.
Sending our $$$ overseas for anything does not help OUR countries economy/employment at all. It has done a complete job of giving other countries the power to dictate our futures etc as you have seen.
2004 Chev 2500HD D/A crew cab LB 4X4 - Air Bags - Loaded
915 Lance Camper with 2'X 8' rear porch (my own design n build)
29 ft Carri-lite 5th wheel - 1 large slide - specially built
36 ft Carriage - 3 axle 5'er -NOW SOLD- Looking at some new 5'ers
Just got back from our 940 mile Christmas visit trip. On the way out we ran 65mph with cruise on. Hand calculated we got 9.1mpg. On the return trip, traffic was very thick and 65mph was giving those wanting to run well over the 70mph speed limit fits. So I bumped it up to 70mph to at least take a little of the difference away. Traffic still passed us like we were running 50mph. On the return trip at 70mph with cruise set we got 7.8mpg. I don't know the exact numbers for wind resistance but, I can tell when riding my Harley that 60mph is a mild breeze and 70mph is a strong wind. It takes more horsepower regardless of at what rpm your engine makes the horsepower necessary to push through the wind. If you want to call it torque, same thing, it takes more torque at whatever rpm your engine runs to push through more resistance be it wind or grade. It takes more fuel to make more torque/horsepower than less regardless what rpm your engine makes it. In summary based on our recent trip, gas and diesel fuel are still dirt cheap at $3 a gallon. It'll have to be way higher for simple economics to makes people conserve. It's still cheaper for us to drag our 5th wheel around at 70mph to sleep in than it would be to take a small car and stay in a hotel. Even if it cost more, it would be worth more to sleep in our own bed in our own little house on wheels than to stay in a nasty hotel room. Just how much more I haven't determined yet.
Our double pane tinted windows, fluorescent light bulbs and lights out habits make our already cheap to own 930sq/ft house pretty efficient.
I'm afraid fueling our RV's will be the least of our problems the way our foreign relations are going.
'05 2500HD Dodge 5.7L Hemi 5spd auto/3.73 SLT. 95k miles
ex '95 Cummins,'98 12v Cummins,'01.5 Cummins,'03 Cummins
'07 KZ Jag 28JFSS.
Hope you had a super trip. We're getting ready to head to Florida for 4 or 5 weeks to visit family after New Years but it will be with the Lance Camper (our Winter Hilton) on the poopdeck and the "V" nosed enclosed trailer pushing us. Both our homes (2,820 sq ft and 4,340 sq ft) have been made extremely energy efficient over the years and use far less than half the KW's of electric and cubic ft of natural gas per year than when built. The savings are great and happen every month of every year and have returned more 4 times the total improvement's cost so far. We laugh all the way to the bank nowadays!
I own a vehicle that uses more fuel at 55 than at 65. My Caddy won't hold OD at 55...it's constantly hunting on hills, which uses more fuel (to say nothing of how hard it is on the tranny). 65MPH, never kicks out of OD.
My wife's friend drives a 2001 Z28 SS...it's spinning <2000RPM at 65MPH. Running 55 means not using high (6th, very tall double OD) gear.
The 55MPH speed limit is in the dumpster where it belongs.
John
1984 Ford B-700 school bus conversion, Thomas body
A bunch of other vehicles
3 nutty cats (Maya, Vierna, Briza)
One lazy dog (Marmaduke)
One wife (Liz)
"A wasted youth is better by far than a wise and productive old age"
-Jim Steinman
Thanks, and wishing you the same on your trip. Hopefully traffic will have thinned out some by then.
We're kind of trapped in our small paid for house. Being close to the Gulf, Allstate cancelled us so there's a big savings. Housing in Florida is out of control and to buy bigger would put us in a new high tax rate, mandatory insurance and higher energy bills. So it's not really a bad trap. Some folks are turning to full timing not just for the mobility but, to avoid Florida's outrageous mortgage, property insurance and energy bills. And if we have to evacuate, they hitch up the house and go.
Not surprising, folks in their 500sq/ft flats in NYC are the most energy efficient people in the US.
I hear what you are saying about the costs and it had a lot to do with our divesting ourselves just in time of our Florida place etc also. Hard to pay those big yearly bills for just a 2-3 month maximum use when the RV's are so practical and comfy. The property/home costs go whether your there or not.
Our shingles are paid for also and we have thought many times about possibly selling the biggies and buying smaller shacks for easier maintenance. With every birthday passing it seems like more and more work! However, now with us (2), our kids and spouses (4), married and unmarried grandchildren (10), and now the great-grandchildren (3) coming over quite often, it'd create more problems than it would solve. All would really miss Lake Michigan and the sand dunes. We would be hard pressed to match our location's many amenities. Location, location, location. Besides, we'd have to redo or build the smaller adobe's completely to meet our expectations of energy efficiency we've come to appreciate. It also would be at today's high costs too. A no-win situation for us also. Bummerland!!!
Actually, we really have it good and don't want to mess it up with a mistake!
It takes 24 minutes more to drive 100 miles at 55MPH than to drive at 70 MPH (distance devided by speed equals ? times 60 equals time).
I drive a 07 Grand Marquis V-8 6.4 liter. I get the same mileage whether it is loaded or empty. The space between the piston and cylinder requires so much vapor to make it go "boom". Of course the more push initiated, the more energy required. GM has engineered minimal pistons to shut down when power isn't required. My Grand Marquis gets 18 in the city and 28 plus on the highway . Not bad for a 4300 lb(curb weight) vehicle. I think every vehicle has their sweet spot determined by lack of carbon build, oil, tires, and mileage. Putting any size cubes to hard core working and there goes the baby with the dish-water. I would probably fall fast asleep driving 55 MPH unless I was cruising the highway in Alaska or other scenic drives.
"Of course the more push initiated, the more energy required"
Exactly. Some people still think their vehicle uses LESS fuel if they go faster... which is true at the lower end of the mph range but not at freeway speeds. Despite all the "in my vehicle" claims, you don't use LESS fuel going 65 than you do going 55, you use MORE... much more.
It used to be that our vehicles reached optimum fuel efficiency at about 40 mph. Giving credit where credit is due, today's manufacturers are building vehicles that are much more efficient.
Most of today's vehicles achieve their optimum fuel efficiency between 45 and 55 mph. Once past 55 mph the fuel efficiency of our vehicels takes a nose dive.
So, given this, the "double nickle" policies of the 1970's were saving the country fuel but they probably could have saved a BUNCH more if they would have made the limit 45 mph.
In today's world the 55 mph speed limit for the sake of fuel conservation is a good match to the actual fuel efficiency of most vehicles rolling down the road today.
* This post was
edited 12/29/07 11:28am by pacificnw *
I have read that the EPA Highway MPG on the window sticker was calculated using speeds under 50 mph. Of course this is unrealistic but it shows that slower speeds return a better mileage figure. I believe that was recently changed to give a more accurate estimate of what most people would obtain. I'm uncertain how they obtain the new figures but they are lower.
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