Driving 55mph instread of 65mph -Just hit 32.5 MPG (honda accord)

[goodoleboy]

I was able to get 32.50 MPG out of my 98 4cyl Accord sedan. Usually if i drive 65mph i get 27.5 mpg. But I drove 55mph on most of the tank. I figure im saving $5 a tank if I drive this slow.

Anyone else drive like a bat out **** like me?

 

[Palut]

27.5 @ 65 mph? Pump your tires up some more.

I've got a '95 Accord 4 cyl, and routinely get 27-29 mpg delivering pizza. A month ago I was limited to 65 mph on I-90 in Montana because of a snowstorm, and I got 34 mpg on that tank! The whole trip (1700 miles) averaged around 30 mpg. I would've gotten better mileage, but I spent most of the trip between 85 & 100 mph.

How many miles does your Accord have?

 

[Ugly3]

My `98 Chrysler T&C Minivan has gotten 31 MPG for a 286 mile trip running 55 MPH. Was not able to test on the way home as my Wife had a gun on me.

 

[goodoleboy]

quote:

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Originally posted by Palut:


How many miles does your Accord have?

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The accord has 115,000 miles on her. Tires are filled to spec. I think actually the tires are a little samller Correct size But Kumho apperantly makes the tire a little smaller than other makes.

 

[loudist]

Windows up or down?
A/C on or off?

Windows down creates significant aerodynamic drag.

 

[oilyriser]

I recently got 31.5 mpg, at 71 mph, in my Legacy, using some aerodynamic modifications (cardboard and masking tape). It should give about 36 mpg at 55 mph, now.

Car makers do not make cars as streamlined as possible. Looks often supercedes efficiency. My car had open mesh covers where the fog lights would go. This probably lost me 0.5% fuel economy, at a cost of c$50 so far. The holes are now plugged.


The Pontiac Sunfire and it's clones have deeply recessed turn signal lights on the front bumper. If you install a sheet of clear plastic over them, making it flush with the bumper, you would gain a bit of extra mileage, maybe 0.1%.

Check the high pressure areas on your car's body, such as the front, for air leaks, and check the high velocity areas, such as the underside, and sides, for disruptions in surface smoothness.

The Honda Insight gets good mileage, not just because of the complicated electronics, but because it has a 0.25 drag coefficient, by using fender skirts, underbody panels, etc. Unfortunately, nobody makes fender skirts for my car, so I had to improvise, using cardboard.

 

[eljefino]

oilyriser, we need pictures.

 

[Russell]

My 95 bmw 525i which epa states 25 mpg for highway will get about 29 to 30 at 55-65 mph. I have seen over 30 for extended highway driving. I consider this great for a 3,500 pound automatic transission car.

I use synthetic fluids in engine, transission and differential with tires at about 33 pounds.

 

[buster]

I drive between 70-80 mph and was able to hit 32.5 mpg.

 

[bigpaulo]

oilyriser, TTIWWOP! (for everyone else who doesn't interact with kids as much, This Thread Is Useless WithOut Photos!)

If you can't host them anywhere, email them to me, I'll give them a good home and point to them here.

 

[brianl703]

According to the ScanGauge, I've gotten 33MPG out of my '96 Ford Contour 2.5L V6 5spd and that's going 65-70MPH.

 

[MAJA]

quote:

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Originally posted by goodoleboy:
I was able to get 32.50 MPG out of my 98 4cyl Accord sedan. Usually if i drive 65mph i get 27.5 mpg. But I drove 55mph on most of the tank. I figure im saving $5 a tank if I drive this slow.........

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Why is this a surprise? I posted similar results and suggested slower driving as a way of increasing mpg in earlier threads, and was "flamed" for suggesting it. Its well known that aero drag increases exponentially in relation to speed. That was the main reason for the "55" mph speed limit change in the early seventies oil embargo era, not for the safety aspect that it was mostly attributed to.

Everyone is into changing plugs/components, adding stuff to their fuel and crankcase, airfilters, hotter ignitions, etc in trying to increase mpg, when the proven slower driving and maintaining tire pressures have a dramatic affect.

But I learned my lesson in earlier threads, in not suggesting anyone change their habits, or for that matter, to do any imaginative thinking.

 

[kenw]

actually the original studies indicated the ideal/avearage speed was 50mph.

Political compromise pushed it to 55mph.

and fyi, aerodynamics really does very little at these speeds on the average car. (but don't tell that to the neighborhood ricer!) Simple rolling friction is the biggest issue to overcome, along with the usual culprits like change in inertia/velocity, gross weight, etc. Riceboy did more harm than good by bolting on all the fiberglass and plastic junk that mommy bought for him; he added weight.

Some high mileage cars have lots of "aerodynamic" doodads because the person who wants one thinks they help.

[ April 20, 2005, 02:01 PM: Message edited by: kenw ]

 

[labman]

Best thinking I have seen in this thread goes to oilyriser and his modifications. Is driving something appropriate for the task, outside imaginative thinking? From the time I filled up a week ago until Monday, my wife and I drove 728 miles with our Ecotec equipped 02 Cavalier. Some of it was around town and 2 lane roads, but most of it was running 70-80 on the Interstate. We were comfortable with the windows up and the air off most of the time. 2 people, a dog or 2, and luggage, 34.1 MPG over all. My time is worth something to me, and it adds up. Back in the days of the stupid 55 MPH, I did some figuring on a 600 mile trip with 2 little kids in the car. Drive 60, it is 10 hours on the road. Drive 75, and it is 8 hours. The more hours on the road, the more breaks you have to take too.

Drive however you please, but don't block the left lane and make me drive your way too.

 

[JohnBrowning]

Does useing duct tape to keep the air from getting under the hood and riseing at speeds in excess of 150MPH count???

Had a Truck once that I could watch the gas needle drop with my foot to the floor board! It got 4-7 MPG on the HWY in overdrive!!

Know a guy that had a reflashed Dakota with HO CAms and Later HRC cam and HO intake manifold. His role pan came off at 135MPH on the Autobahn!! How is that for demonstration or speed realted drag forces!

 

[DockHoliday]

I was driving on a deserted 2 lane highway late one night when I noticed how quiet it was - no wind noise whatsoever. I figured I must have a really strong tail wind, so I checked the MPG on the trip computer. It showed 76 MPG! I normally would be getting around 30.

 

[Palut]

quote:

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Originally posted by oilyriser:
Car makers do not make cars as streamlined as possible. Looks often supercedes efficiency.

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Two words: Scion xB.

quote:

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Originally posted by MAJA:
Why is this a surprise? I posted similar results and suggested slower driving as a way of increasing mpg in earlier threads, and was "flamed" for suggesting it. Its well known that aero drag increases exponentially in relation to speed. That was the main reason for the "55" mph speed limit change in the early seventies oil embargo era, not for the safety aspect that it was mostly attributed to.

Everyone is into changing plugs/components, adding stuff to their fuel and crankcase, airfilters, hotter ignitions, etc in trying to increase mpg, when the proven slower driving and maintaining tire pressures have a dramatic affect.

But I learned my lesson in earlier threads, in not suggesting anyone change their habits, or for that matter, to do any imaginative thinking.

---

I think we're more into changing parts and overinflating tires (up to sidewall pressure) than we are into driving slow...because, IMHO, driving slow sucks! No offense, if its worth it to you to drive slow to save gas, more power to you! But for me, I CAN'T STAND going less then 70 on the freeway at a minimum!

I took this girl to a Seattle Mariners game last summer; Seattle is 60 miles from my house. As we left town, I asked her if she would mind if I sped. She said she wouldn't like it, so I set the cruise at 65 and parked in the middle lane. It was HORRIBLE!!! I felt like I'd been driving forever when I reached Tacoma, and that's only 30 miles! I'm used to covering the 60 miles to Seattle in 40-45 minutes, not a whole hour!!

When people use the phrase "going a mile a minute", I think, "Why would you ever want to go that slow?!?!?!?"

 

[kenw]

quote:

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Originally posted by JohnBrowning:
Does useing duct tape to keep the air from getting under the hood and riseing at speeds in excess of 150MPH count???

Had a Truck once that I could watch the gas needle drop with my foot to the floor board! It got 4-7 MPG on the HWY in overdrive!!

Know a guy that had a reflashed Dakota with HO CAms and Later HRC cam and HO intake manifold. His role pan came off at 135MPH on the Autobahn!! How is that for demonstration or speed realted drag forces!

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John, aerodymanmics does enter the equation at higher speeds certainly. My point was at the 50-60 range that most cars are designerd to operate at and hence the fuel economy numbers are based upon.

I'll assume a roll pan is a large flat part of some sort. Large flat things usually don't fly off vehicles because of drag. They fly off due to LIFT.

they lift up and the vehicle runs out from under them......

the reason the hood lifts is due to negative pressure ABOVE the hood since the air above is moving much faster and the curvature on or before the hood will create a partial vacuum, like an aircraft wing does.

and no, duct tape really doesn't fix it by keeping air from getting under it and lifting it. (altho it might keep it from lifting at all by simply holding it down and hence someone may THINK it fixed it by "sealing" off the air.)

I'll bet the Germans really appreciated the extra cr@p flying about on their freeway.... BTW, was there again last month. Much of the "Autobahn" has speed limits of 120kph which like here are routinely ignored. Drove from Munich to near Frankfurt, max posted we saw was 140kph. Only a few short sections had no limit and that was only in a single lane. (120kph=~75mph)

Crusied for quite awhile at 220kph in a new Volvo diesel station wagon while I was there last month. Hardly an "aerodynamic" vehicle, but at least no parts came off....

[ April 20, 2005, 04:06 PM: Message edited by: kenw ]

 

[labman]

Doing some more figuring. 15 gallon tank times 34 mpg running 75 mph = 510 miles on a tankful, about $30, and 6.8 hours. Now if running 60 gives me 25% more mpg, the 510 miles would take 8.5 hours and $22.50, or $4.41/hr, $2.20 for each of us, if my wife is along. Gas is going to have to go to about $5/gal before we make the minimum wage.

 

[JHZR2]

quote:

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Originally posted by Palut:
I think we're more into changing parts and overinflating tires (up to sidewall pressure) than we are into driving slow...because, IMHO, driving slow sucks! No offense, if its worth it to you to drive slow to save gas, more power to you! But for me, I CAN'T STAND going less then 70 on the freeway at a minimum!

I took this girl to a Seattle Mariners game last summer; Seattle is 60 miles from my house. As we left town, I asked her if she would mind if I sped. She said she wouldn't like it, so I set the cruise at 65 and parked in the middle lane. It was HORRIBLE!!! I felt like I'd been driving forever when I reached Tacoma, and that's only 30 miles! I'm used to covering the 60 miles to Seattle in 40-45 minutes, not a whole hour!!

When people use the phrase "going a mile a minute", I think, "Why would you ever want to go that slow?!?!?!?"

[/QB]

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Go ahead and speed, I dont care. But what I do care about is when the speed differential is VERY large. It doesnt matter what you think of the other drivers, if theyre going 60, then you really shouldnt go faster than 70. Its a safety thing. Especially if swerving and SUVs/big trucks are involved. This is my major gripe about people who insist on driving very fast on roads.

On an empty road, go as fast as you care to. If you get pulled over, its not my dime. But when others are on the road, its important to keep the delta small.

As far as speed/MPG goes, I think it entirely differs from car to car. My BMW does best at ~71. My saab is better at ~55-65 mph, and it has a super low Cd of approximately 0.27, and double overdrives. My MB diesel didnt matter what speed it was driven at, 50 or 80 was about the same. My truck does good high and does good low, comapred to the MPG at 70. Its like it hits a bad groove at 70 mph, and MPG is lower at sustained cruising at 70 than higher or lower. But the funny thing is that it easily cruises at 70, easier that any other speed; its like it falls into that speed.

JMH

[ April 20, 2005, 09:17 PM: Message edited by: JHZR2 ]