hyeglenn
Champion Author
Fresno
Posts:1,070
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Message Posted: May 20, 2013 8:53:10 AM
It matters how old your car is?
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dfd1983
Rookie Author
Florida
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Points:107,620
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Message Posted: May 18, 2013 2:21:24 AM
When driving 80 mph, my truck gets about 13 mpg. At 60 mph, it gets about 21 mpg... In my case it pays to slow down a bit.
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speedy700
Veteran Author
New Jersey
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Message Posted: May 18, 2013 12:09:08 AM
I have found that I get the best mileage between 60-65 MPH and anything over 75 MPH really starts to eat away at the mileage.
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StArrow68
Champion Author
Oakland
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Message Posted: May 17, 2013 11:45:01 AM
Just because you believe something, that doesn't make it true.
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blckwolf
Veteran Author
North Carolina
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Message Posted: May 15, 2013 7:37:12 PM
I don't think that speeding results in much difference in gas mileage - the good old U.S. Government used to try to claim that driving 55 MPH was the most fuel efficient speed. That was proven wrong multiple times by various studies as I understand it. The true actual most efficient speed varies from vehicle to vehicle, and has a lot to do with the aerodynamics of the vehicle, the friction from the engine, drive train, and the tires rolling on the road, the amount of braking you do, whether you drive with the AC on or windows down, the available HP of your engine at a given speed, and the amount of torque your drive train produces. Also, all combustion engines are very inefficient when it comes to fuel consumption because much of the energy used burning the fuel is transferred into heat, which is really just wasted energy. Smaller engines usually produce more heat than larger ones, and smaller drive trains do as well. In general though, it is generally given that most vehicles achieve peak fuel economy at between 65 MPH and 75 MPH, and that they are most inefficient at speeds below 25 MPH.
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eyegotgas2
Champion Author
British Columbia
Posts:1,091
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Message Posted: May 15, 2013 3:43:14 PM
People will speed no matter what the gas mileage is. I have tried adjusting speed to improve mileage with no obvious differences.
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StArrow68
Champion Author
Oakland
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Message Posted: May 15, 2013 1:07:16 PM
Hummmmm, Vland....., your grasp of rpm and the link to mph ignores just one minor issue. Once the manual is in top gear, the link between rpm and tire rotation is fixed, or as close to fixed as is worth worrying about. So to increase mph you need to add rpm, which uses more fuel than running at lower rpm. Add in wind resistance and the required rpm's go up a bit. What you seem to say is that adding rpm's happens before the speed increases, I'm thinking that what the fuel does is increase torque to accelerate but that doesn't change the link between rpm's and mph.
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Valandingham
Champion Author
Washington
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Message Posted: May 15, 2013 1:44:05 AM
63pioneer if you think Driving 55 is better on Fuel Economy then you can just Stay off the freeway.
Weaslespit, and mybigtruck, the ones that I cannot understand are those who use more fuel over a longer distance and time to get up to speed, instead of 1 quick Rapid Acceleration over a Shorter distance and time to get up to the posted speed limit. Yes you do use LESS FUEL at a Constant Higher Speed and your RPMs at 65 and 70 are right around the same. Here is why.
As you get your vehicle up to speed your vehicles RPM’s are turning much higher. Once your vehicle is up to speed the engine’s RPMs Drop just enough to assist the vehicles mass to maintain it’s forward Momentum the higher speed limit. If your vehicle’s engine were to stop while your vehicle is in motion it will continue to move forward as you coast down the road until you either slow to a stop or you apply the brakes to bring it to a stop. In most automatic vehicles you have to apply the brakes in order to place your vehicle into Neutral. If you’re driving a Manual Transmission vehicle you can just push in the clutch and keep going down using the vehicle’s mass and forward motion. This is why Vehicles with a Manual Transmission gets better fuel economy than vehicles with an Automatic Transmission.
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Wrench45840
Rookie Author
Ohio
Posts:64
Points:15,335
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Message Posted: May 14, 2013 11:41:30 PM
I just set the cruse at 75MPH and run. Todays cars do ok as long as the check engine light is off and use overdrive!!
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krazkar
Veteran Author
Calgary
Posts:280
Points:274,525
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Message Posted: May 14, 2013 11:17:15 PM
Fine with me. When I am in the States, I like the higher speed limits. It don't matter if my fuel burns faster. Gas is cheaper in the States also. I have no problem buying more fuel as I travel.
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63pioneer
Champion Author
Texas
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Message Posted: May 13, 2013 4:53:52 AM
I find that if I keep my speed at a steady 55 mph my mileage is the highest. When they reduced the max speed limit down to 55 mph. It was the best thing to do when you had to sit in line to get gas and hope there was still some left went your turn came. Don't miss the waiting, but miss the lower prices!
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dontuknowOH
Champion Author
Ohio
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Message Posted: May 13, 2013 3:20:21 AM
I have never found a vehicle yet that wouldn't use more fuel at speeds above 50 mph. Vehicles that have modern positive lock-up torque converters after going into top gear cruising mode, then generally the drivetrain is in positive ratios with engine rpms, similar to driving a standard manual shift.
As speed goes upward engine rpms go upward but throttle opening position also goes a bigger % farther because of aerodynamic resistance on many vehicles gets greater, think about wind force and what it can do at 70 mph,80... 90... 100 mph. or more (storms)! That is what happens to the front of your vehicle with wind velocity on the frontal areas top to bottom of your ride at high speeds.
There are times when a tailwind can reduce the forward motion resistance somewhat for a mileage increase in a given direction(lucky benefit) at that! Inside vehicle with windows up wind benefits are hard to detect. Throttle position/MPG read-outs/speedometer readings are more accurate for judging fuel savings along with knowing tire pressures.
Engines simply pump in air/fuel then convert with heat expansion produce rotation motion to propel the car. The fuel energy used up is at the GO PEDAL >>>> opening, works sort like a faucet, more opened = more fluid gets by, and used up per mile, maybe...... I just dreamed that ETC.
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Weaslespit
Champion Author
Cincinnati
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Message Posted: May 12, 2013 6:49:11 PM
"I can never understand the ones who knowingly accelerate into the next red light, slam on the brakes, and then repeat."
100% agree! In-fact, many get upset with me as I coast to the red; they accelerate, cut over and then slam on their brakes. I give them the applause and thumbs-up that they so richly deserve...
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Weaslespit
Champion Author
Cincinnati
Posts:8,851
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Message Posted: May 12, 2013 6:47:48 PM
"But when your driving a Gasoline Powered vehicle and your traveling a constant 65 miles per hour your vehicle is running around the same RPM's as you are doing 70 Miles Per Hour. Which means your getting further down the road on the same amount of fuel."
This couldn't be more wrong. I hope you don't have an engineering degree...
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mybigtruck
Sophomore Author
San Jose
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Message Posted: May 12, 2013 1:08:59 PM
I can never understand the ones who knowingly accelerate into the next red light, slam on the brakes, and then repeat.
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hooky
Champion Author
Michigan
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Message Posted: May 11, 2013 6:19:25 PM
It does up to a point.
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dontuknowOH
Champion Author
Ohio
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Message Posted: May 8, 2013 10:32:42 PM
An accurate fuel flow meter, which most vehicles don't have, then compared to average economy cruise speed (Sweet-Spot.... which could change due to terrain encountered/wind conditions (running in top gear). Modern engines get controlled constantly by their ECM systems automatically, often unnoticed by the driver.
The engines performance therefor can cover peaks over a wider range of loads/rpms with the auto trannies help of gearing changes(tricky stuff) and successful..... Tune-ups fade into the limelight in most cases....
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GLM4205
Champion Author
Toledo
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Message Posted: May 8, 2013 6:05:01 AM
It does help saving gas but it depends on the individual whose time may be more impotant than saving on gas..
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Valandingham
Champion Author
Washington
Posts:7,770
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Message Posted: May 8, 2013 3:30:05 AM
Everyone, going faster at a constant will Increase your fuel economy. The only way that your Fuel economy goes down at higher speeds is when you have to Slow Down for the Slower Driver in front of you that is IMPEDING TRAFFIC. If you think that Driving Slower is better for your Fuel Economy then you must be driving an Electric Vehicle were driving faster reduces your distance traveled on the batteries. But when your driving a Gasoline Powered vehicle and your traveling a constant 65 miles per hour your vehicle is running around the same RPM's as you are doing 70 Miles Per Hour. Which means your getting further down the road on the same amount of fuel. If you want the illustrated version then take a good look at the difference between of your vehicle MPG Rating at 35 Miles Per Hour(City) and your vehicles MPG Rating at 65 Miles Per Hour(Highway). Which One gets you further down the road on the same amount of fuel?
Here is something that you all need to do. Take your vehicle Full up the tank. Drive a constant 65 Miles Per Hour on the freeway until you use 1/4 tank or close to a 1/4 of a tank and see how far you go. Write this information down. Top Off your tank then drive on back roads and surface streets at 35 miles per hour until you use close to the same 1/4 tank then take down this information and see which one gets you further.
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dontuknowOH
Champion Author
Ohio
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Message Posted: May 8, 2013 12:59:42 AM
I believe so. Try this; >>> First pick the highest cruise you like to often drive then take note of the engine rpm @ that speed.
Later when while stopped at a traffic light, place vehicle in neutral and apply your foot to the Go Pedal and raise your engine RPM's to that same setting and hold for about two seconds and look at the Driver across from you in the next lane, check their facial expression..........
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krazkar
Veteran Author
Calgary
Posts:280
Points:274,525
Joined:May 2012
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Message Posted: May 7, 2013 9:46:33 PM
Is this for real? Better lower the speed limits so The government can save me some gas. Then again, if the speed limits were higher, I wouldn't be 'speeding' as much. So I guess then I would save gas!
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gougedQC
Champion Author
Montreal
Posts:5,130
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Message Posted: May 7, 2013 9:28:53 PM
lets say you have to travel 120 miles...at 60 its 2 hrs at 75 a tad over 1.5 hrs...saving .5 hours..
i dunno about you, but an extra 30 minutes sitting in the car is not nearly as much fun as an extra 30 sitting in the shade with a cool drink chatting with friends. 80mph would be even better...
I you want to drive 55 feel absolutely free to do so, with my blessing. but please could you stay out of the left lane?
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giwan
Veteran Author
Michigan
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Message Posted: Mar 29, 2013 9:36:30 PM
Speeding is relative.
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Remotecontrol
Sophomore Author
Ottawa
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Message Posted: Mar 29, 2013 4:04:04 PM
I've noticed most of the drivers heading down the road well above the speed limit are driving "economy cars". I guess they figure because they getter better gas milage it does not matter.
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51stovi
Sophomore Author
Nashville
Posts:125
Points:83,715
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Message Posted: Mar 29, 2013 2:51:18 PM
To quote the group Alabama:
I'm in a hurry to get things done
(oh,) i rush & rush until life's no fun
All i really gotta do is live & die
But, i'm in a hurry & don't know why
Don't know why
I have to drive so fast
My car has nothing to prove
It's not new, but it'll 0-60 in 5.2, oh
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dontuknowOH
Champion Author
Ohio
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Message Posted: Mar 29, 2013 9:00:41 AM
@ Shockjock 1961 Hi, I just read your post and assuming the speed limit was 60mph. If that is the case scenario you would have to drive 50% faster than 60 mph. at then + 90 mph at least to gain 25 min. of initial time for a 100 mile jaunt, at a constant 90 mph.
For any other increased speed zone base, add 10 seconds per mile for each 10 mph. increases. Or 5 sec. per each added 5 mph. increase of speed.
That would again change if the required minutes to be gained is also changed. This gets too erratic to even consider, because the driver might start sneezing, that alone could up-set the whole system of worrying about time..... instead of a fuel savings It takes twenty second to blow ones nose still today...... I can be wrong... Happy driving !
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Jmac2008
Champion Author
Missouri
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Message Posted: Mar 29, 2013 4:19:00 AM
even if we slow down they will just raise the price more to compensate for lost revenue.
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Mr1lung
All-Star Author
Phoenix
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Message Posted: Mar 29, 2013 1:54:29 AM
??
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gasandgoAL
Champion Author
Alabama
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Message Posted: Mar 29, 2013 1:37:23 AM
slow down and smell the roses
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chipote
Champion Author
Washington
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Message Posted: Mar 28, 2013 11:52:23 PM
Because we have no time
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tdioiler
All-Star Author
Detroit
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Message Posted: Mar 28, 2013 10:34:53 PM
So everyone here believes that all cars operate at the same efficiency across the speed band?
They don't.
Look at the Prius. The better fuel MPG is using city driving under 55. At highway speeds greater than 60, the MPG goes down.
Comparison with the 2006 Dodge Magnum. MPG goes up with speeds greater than 60. Actually best MPG is closer to 75 due to trans and engine specs to meet autobahn speeds.
But half the consumption? Don't think so. The 70's speed change only affect at best about 20% reduction. Most studies where much less. Hence the expensive change back to higher speeds(the highway sign lobby must have been very powerful that year!).
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chuckl95453
Veteran Author
California
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Message Posted: Mar 28, 2013 1:49:06 PM
Yes, so slow down if you want to.
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IAMCANADIAN73
Champion Author
Ontario
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Message Posted: Mar 28, 2013 7:11:41 AM
Yep
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IAMCANADIAN73
Champion Author
Ontario
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Message Posted: Mar 28, 2013 7:11:31 AM
Sure does
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Shockjock1961
Champion Author
Illinois
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Message Posted: Mar 27, 2013 9:06:02 AM
"It is a trade off. If you have to go 100 miles the difference is 25 minutes."
You must not be very good with math. DO you know how far you would have to exceed the speed limit on a highway or interstate to save 25 minutes on a 100 mile trip?
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GasManKB
Rookie Author
California
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Message Posted: Mar 26, 2013 9:15:55 PM
Who told you that !
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davisadm
All-Star Author
Los Angeles
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Message Posted: Mar 25, 2013 6:03:55 PM
It is a trade off. If you have to go 100 miles the difference is 25 minutes. If you go a couple of mile, the difference is negligible.
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5p33df73ak
Sophomore Author
Gary
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Message Posted: Mar 25, 2013 2:49:09 PM
Thats very true but sometimes you have to go faster say like on a highway of a speed limit of 70, like you can go slower if you want but depending on the road conditions it will be better to go 70
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gwhizz13
Veteran Author
Abbotsford
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Message Posted: Mar 25, 2013 7:36:32 AM
It is better for us to slow down, is it because we are late getting started, leave everything to the last minute?
We just want to get somewhere in a hurry!
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IAMCANADIAN73
Champion Author
Ontario
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Message Posted: Mar 25, 2013 7:27:32 AM
Sure does
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IAMCANADIAN73
Champion Author
Ontario
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Message Posted: Mar 25, 2013 7:27:23 AM
Yes
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carinthuist
Champion Author
San Francisco
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Message Posted: Mar 25, 2013 12:33:42 AM
Yes driving slower is better for mpg
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giwan
Veteran Author
Michigan
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Message Posted: Mar 24, 2013 9:34:56 PM
So just how SLOW should people drive? How about 45mph? Maybe 30? Please reference where not speeding will cut consumption in half
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fmttu
Sophomore Author
Texas
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Message Posted: Mar 24, 2013 9:32:09 PM
I have a Taurus with mpg display and I can tell a 2-3 mpg advantage by slowing down from 70 mpg to about 63-64 mpg. I'm usually not in a hurry so I set the cruise at about 65 for beter gas mileage.
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5p33df73ak
Sophomore Author
Gary
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Message Posted: Mar 24, 2013 6:46:39 PM
Very true
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dontuknowOH
Champion Author
Ohio
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Message Posted: Mar 19, 2013 1:28:39 AM
Modern ECM controled engines with variable cam timing can finetune the engine while at midrange power delivery, much better than the older engines,that had fixed cam timing,EFI control/air intake mass is more precise over wider ranges of engine temps along with better tracking of engine loads at cruise speeds/atmospheric pressure changes.
These advantages all help mileage and performance on lower octane fuel,still a four cycle engine only has one power stroke against three momentum strokes per each cyl.= 25% productive X the amount of cylinders.
Kind of like four close candles placed together,only one burning,but three others melting away.... with 25% light output....
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carinthuist
Champion Author
San Francisco
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Message Posted: Mar 18, 2013 11:27:36 PM
yes from experience with HHR at 60mph higher gas mileage 30 plus mpg on highway
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GrumpyCat
Champion Author
Alabama
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Message Posted: Mar 18, 2013 10:54:23 AM
tazdriver is overly simplifying things. Sadly this "dumbing down" is widely practiced in government.
"Speeding" is defined as driving in excess of the posted speed limit. Clearly there is nothing magic about MPG under the posted speed limit vs over the posted limit. One isn't suddenly "wasting fuel" the moment the posted limit is exceeded.
My 2000 Avalon got best MPG at 67 MPH. Never got less than 30 MPG (with calculator at the pump) on 70 MPH roads. Never got over 27 MPG on 60 MPH roads.
And then there is always the question of how much is your time worth?
This winter I drove my ML320BT 1000 miles no faster than 60 MPH and got 31 MPG! Same trip this summer with CC at 70 MPH produced 29 MPG. The same route as Avalon got 30 to 34 MPG. Prius gets 44 MPG.
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Weaslespit
Champion Author
Cincinnati
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Message Posted: Mar 18, 2013 10:53:30 AM
"So it is baloney to say that studies show that economy can double by driving slower."
20% increase in fuel efficiency after changing my commute speed from 75 to 65 in the each way. It isn't so much the constant velocity difference rather than the constant re-accelerating to 75 after getting behind slower traffic that really makes the difference.
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hooky
Champion Author
Michigan
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Message Posted: Mar 18, 2013 9:59:41 AM
Can't say I disagree.
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