Other Talk "Otterville"

Slow Down!

Old 05-06-08, 01:15 PM
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I heard this one before, I don't know how true it is but...

Don't you get better (or worse) MPG depending on the speed you are driving? For example, if you drive at a constant speed of 65 you will get more MPG than if you were driving at a constant 40? Also, doesn't this "ideal speed" differ between cars? I never kept an exact record of it but I always felt that when I drive at a constant 70mph I was getting better gas mileage than when I was driving at a constant 60mph.

It costs damn near $90 now to fill up my tank. I usually fill up every two weeks unless I go on a road trip. I almost never use heat or A/C, unless in "extreme" weather (below 55, above 80). When its cold I wear my coat in the car, when its hot I drive with the window down. Maybe it helps, maybe it doesn't. At the end of the day I'm filling up my car every 2 weeks or so and it costs me about $90 each time.
Old 05-06-08, 01:22 PM
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Originally Posted by Goat3001
I heard this one before, I don't know how true it is but...

Don't you get better (or worse) MPG depending on the speed you are driving? For example, if you drive at a constant speed of 65 you will get more MPG than if you were driving at a constant 40? Also, doesn't this "ideal speed" differ between cars? I never kept an exact record of it but I always felt that when I drive at a constant 70mph I was getting better gas mileage than when I was driving at a constant 60mph.

It costs damn near $90 now to fill up my tank. I usually fill up every two weeks unless I go on a road trip. I almost never use heat or A/C, unless in "extreme" weather (below 55, above 80). When its cold I wear my coat in the car, when its hot I drive with the window down. Maybe it helps, maybe it doesn't. At the end of the day I'm filling up my car every 2 weeks or so and it costs me about $90 each time.
Driving with the windows down is costing you more gas than running the air conditioner. MPG has to do with load on the engine, not necessarily the speed.
Old 05-06-08, 01:25 PM
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What's pathetic is that I remember my parent's Datsun Sunny/210 wagon in 1977 used to get right around 35 MPG in everyday driving and 50 MPG on the highway (my parents used to track it carefully as they could use gas as a tax write-off). That's about what a Prius gets now. Admittedly, the Datsun's engine produced about as much forward thrust as a mouse fart and the car was about as safe in a crash as a cardboard box, but it was enough to get our family of six around for a few years. Two adults in front, three kids in the middle and me crammed in the back.

We all need to get used to 100hp/40MPG cars again, IMO. I'm planning on getting a Nissan Cube when it becomes available late this year / early next year.

Last edited by Hiro11; 05-06-08 at 01:27 PM.
Old 05-06-08, 01:32 PM
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Originally Posted by Brian Shannon
Driving with the windows down is costing you more gas than running the air conditioner.
Not true in stop and go traffic, windows down is better by a long shot.

The difference between running the AC and having the windows down at 60mph constant on the highway is minimal and I think that is what you were getting at.


The brakes waste more gas than anything else
Old 05-06-08, 07:59 PM
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Originally Posted by Hiro11
What's pathetic is that I remember my parent's Datsun Sunny/210 wagon in 1977 used to get right around 35 MPG in everyday driving and 50 MPG on the highway (my parents used to track it carefully as they could use gas as a tax write-off). That's about what a Prius gets now. Admittedly, the Datsun's engine produced about as much forward thrust as a mouse fart and the car was about as safe in a crash as a cardboard box, but it was enough to get our family of six around for a few years. Two adults in front, three kids in the middle and me crammed in the back.

We all need to get used to 100hp/40MPG cars again, IMO. I'm planning on getting a Nissan Cube when it becomes available late this year / early next year.
If you want good MPG, you can get the new Jetta hybrid...it's supposed to get close to 70 MPG.
Old 05-06-08, 08:00 PM
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Originally Posted by 4KRG


The brakes waste more gas than anything else
true...you're much better off playing "bumper cars"...that way you save gas and brake pads/rotors. and it'd be a bonus if you get stuck to the car in front of you...that way you don't have to waste any gas either!
Old 05-06-08, 08:05 PM
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Originally Posted by Brian Shannon
No.

I just want to get where I am going without getting killed.
So you speed your way where you are going so you...don't get killed?

Isn't driving faster/more aggressively than other people one of the main reasons people get in accidents???

And regarding price...please be sure to bump this post in another two years when oil is selling for $200.00 per barrel and approaching six bucks a gallon, big spender!

To clarify: I am NOT proposing going dangerously slower than other traffic. I travel mainly in the city, not on the highway, to work, so my commute is on roads ranging from 35 to 45 mph. For most of the trip, the road is 35 mph, but people tend to speed, zipping in and out of traffic. I used to be one of those...trying to go 45 or faster on those roads. Slowing down to regular speed limit has helped and I still get to work on time.

Last edited by calhoun07; 05-06-08 at 08:19 PM.
Old 05-06-08, 08:11 PM
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Originally Posted by Goat3001
I heard this one before, I don't know how true it is but...

Don't you get better (or worse) MPG depending on the speed you are driving? For example, if you drive at a constant speed of 65 you will get more MPG than if you were driving at a constant 40? Also, doesn't this "ideal speed" differ between cars? I never kept an exact record of it but I always felt that when I drive at a constant 70mph I was getting better gas mileage than when I was driving at a constant 60mph.

It costs damn near $90 now to fill up my tank. I usually fill up every two weeks unless I go on a road trip. I almost never use heat or A/C, unless in "extreme" weather (below 55, above 80). When its cold I wear my coat in the car, when its hot I drive with the window down. Maybe it helps, maybe it doesn't. At the end of the day I'm filling up my car every 2 weeks or so and it costs me about $90 each time.
You raised some good questions...which raise questions from me...

Does using your cruise control on long trips help out your MPG?

Does using your heat/AC really effect your fuel efficiency? I thought the heat was more electrical/based off the heat of the engine than it was gas, and I am pretty sure your AC doesn't really burn more gas. I don't really recall...which is why I am asking...I thought Mythbusters did an episode on this a few years back.
Old 05-06-08, 08:14 PM
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Originally Posted by D.Pham00
If you want good MPG, you can get the new Jetta hybrid...it's supposed to get close to 70 MPG.
http://www.hybridcenter.org/hybrid-timeline.html

* Est. release date: 2009 (if at all)
* What we know: The most recent reports on the VW Jetta Hybrid would have a hybrid drivetrain coming out in 2009 along with the planned redesign of the vehicle. However, that was under Bernd Pischetsrieder, VW's CEO that was replaced in November 2006. The new regime led by Martin Winterkorn is quoted as believing that the profit margin on "economy hybrid" models is far too low, and is planning to turn their attention to the Touareg SUV as its most likely hybrid premiere.
Old 05-06-08, 08:14 PM
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i've started to slow down to 55-65 on the highways, and it does indeed work. i saved about 30-35 miles. however, i only go 55 if i'm driving an hour or less; anything more, and i'll drive the speed limit. i researched this idea; it's all physics, wind resistance, and the fact that american cars are built for and optimal mpg of 55. anything more that 55, and you'll be getting less than what the meter says. plus, you are less likely to get into an accident driving slower, your brake time increases, no tickets, etc...etc...it's just smart.

Last edited by joeee; 05-06-08 at 08:18 PM.
Old 05-07-08, 07:31 AM
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Well if slowing down saves gas, then shouldn't sitting at light be the most fuel efficient? After all, you can't go much slower.
Old 05-07-08, 07:44 AM
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Originally Posted by D.Pham00
If you want good MPG, you can get the new Jetta hybrid...it's supposed to get close to 70 MPG.
Non plug-in hybrids are a bunch of hooey in my opinion. Their big value-add is regenerative braking which is extremely inefficient and somewhat suspect. I'm convinced that the Prius gets (relatively) good gas mileage because it has a small, low powered gasoline engine and good aerodynamics, not because of the hybrid drivetrain. Also, a typical Euro-spec diesel hatch generally offers much better mileage (a diesel VW Polo, for example, can easily hit 70 MPG) at a much lower cost. There's a reason the Prius hasn't done very well in Europe: it doesn't make sense when you have simpler, cheaper cars that have better MPG.
Old 05-07-08, 08:05 AM
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So you speed your way where you are going so you...don't get killed?
I don't think about saving gas when I am driving. I drive the way I need to and in my area that is usually defensively. The notion of slowing down is about as valid as asking people to stop wasting gas. Not going to happen.
Old 05-07-08, 08:19 AM
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Don't know if it's been mentioned but how hard you accelerate makes a big difference too. I laugh when I see somebody almost floor it on a green light only to top out at 5 mph under the limit, or have to stop again at the next light.
Old 05-07-08, 09:02 AM
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Originally Posted by calhoun07
You raised some good questions...which raise questions from me...

Does using your cruise control on long trips help out your MPG?

Does using your heat/AC really effect your fuel efficiency? I thought the heat was more electrical/based off the heat of the engine than it was gas, and I am pretty sure your AC doesn't really burn more gas. I don't really recall...which is why I am asking...I thought Mythbusters did an episode on this a few years back.
Using cruise control helps a lot from what I've seen. Like I said, I don't keep exact records but I know that cruise control is helping.

I don't know about your second question. Typically I prefer not to use ac or heat anyway, unless in extreme conditions. If its warm out I'd rather drive with the window down. If its cold, I'll use the heat but if its bearable I'll just turn it off. I remember mythbusters did something with fuel economy and windows down vs. AC. I can't remember the outcome.
Old 05-07-08, 09:43 AM
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Originally Posted by Goat3001
Using cruise control helps a lot from what I've seen. Like I said, I don't keep exact records but I know that cruise control is helping.

I don't know about your second question. Typically I prefer not to use ac or heat anyway, unless in extreme conditions. If its warm out I'd rather drive with the window down. If its cold, I'll use the heat but if its bearable I'll just turn it off. I remember mythbusters did something with fuel economy and windows down vs. AC. I can't remember the outcome.
http://kwc.org/mythbusters/2004/11/m..._catapult.html

I guess it was later pointed out that the break-even point is about 50mph. Above that, and it's better to use the A/C (more drag from the windows). Below, windows are better.

I'm all for saving money. But I'd rather have the extra 2 minutes at home that I save by driving faster than a few dimes in gas savings. Time is precious.

BTW: the highway speed thing depends. I think 6-cylinders and greater are better at highway speeds...it depends partially on the gearing of your engine. Driving slower doesn't get you a whole lot of net gain in a bigger engine. If you're cruising at low RPMs I would think it wouldn't really matter too much what the speed is.

Last edited by GreenMonkey; 05-07-08 at 09:51 AM.
Old 05-07-08, 10:22 AM
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Originally Posted by taa455
Don't know if it's been mentioned but how hard you accelerate makes a big difference too. I laugh when I see somebody almost floor it on a green light only to top out at 5 mph under the limit, or have to stop again at the next light.
I feel that this makes the biggest difference overall. Jackrabbit starts use fuel in huge gulps. Gentle acceleration is THE key component in an overall mileage improvement regimen.
Old 05-07-08, 10:32 AM
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Originally Posted by fujishig
Agreed, you can increase your gas mileage by not taking so many unnecessary short trips.

There's some new fangled term called hyper-miling which just seems to be a collection of techniques to save gas, including such simple things as not accelerating as quickly to techniques like turning off the engine when at coasting speed (!), filling your car tires up with nitrogen, and drafting behind other cars.

Of course, if you're already driving a non-fuel-efficient vehicle, what are the chances you care enough to do these things?
I've got a 2000 Ford F-150 with a 25 gallon tank. I've never got more than 380 miles to the tank, averaging close to 16mpg. I was always heavy on the gas, heavy on the brake. When gas went up I started reading up on hypermiling. http://www.cleanmpg.com/

So, I maxed inflated my tires according to the sidewall, changed to synthetic 5w30, replaced the air filter, fuel filter, cleaned the maf. I eased into the speed, went the speed limit, coasted to brake and quit using ethanol mix gas. Also looked at the tach more than the speedometer to see when the next gear shifted the rpm's down and timed my increase in speed accordingly.

Now I've actually had 400 miles and still had a quarter tank of gas left and have averaged 23mpg.

I was skeptical at first but now I believe.
Old 05-07-08, 10:50 AM
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That's a good idea, in theory, but it can't work like it used to.

About 10 years ago, there was a road I used to take regularly that started on top of a hill, and I would throw my car into neutral and coast for at least a few miles until a light. Now, there's at least 5 lights along that road where there used to be none - and I'm lucky if I hit a green on just one of them.

It seems like more now than ever, there are not just more traffic lights, but that I hit a red at every single intersection. So now, not only do we have way more expensive gas, we use more because there's more street lights that turn red way more often than ever before.
Old 05-07-08, 12:44 PM
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Originally Posted by slop101
That's a good idea, in theory, but it can't work like it used to.

About 10 years ago, there was a road I used to take regularly that started on top of a hill, and I would throw my car into neutral and coast for at least a few miles until a light. Now, there's at least 5 lights along that road where there used to be none - and I'm lucky if I hit a green on just one of them.

It seems like more now than ever, there are not just more traffic lights, but that I hit a red at every single intersection. So now, not only do we have way more expensive gas, we use more because there's more street lights that turn red way more often than ever before.
I was telling this to a few people the other day. Although the traffic was heavier on Long Island, we do twice as much driving from light to light here in upstate. Those damn lights outside industrial and business parks are the biggest waste. They're only needed a couple hours a day. We build more commercial space then throw up a few more lights. We have light 20 or 30 yards apart and it's easy to get stuck at both of them.
Old 05-07-08, 08:24 PM
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Originally Posted by taa455
Don't know if it's been mentioned but how hard you accelerate makes a big difference too. I laugh when I see somebody almost floor it on a green light only to top out at 5 mph under the limit, or have to stop again at the next light.
I find myself watching the RPM gauge more than the MPH gauge. I try to keep it under 2000 RPMs, and I find that has been helping me in my fuel efficiency. Not accelerating hard, of course, helps keep the RPMs low.
Old 05-07-08, 08:40 PM
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Originally Posted by slop101
It seems like more now than ever, there are not just more traffic lights, but that I hit a red at every single intersection. So now, not only do we have way more expensive gas, we use more because there's more street lights that turn red way more often than ever before.
Just about all the traffic lights I encounter seem to be timed to turn red at exactly the amount of time it takes you to go from the previous light to the next one at the speed limit. Well...not seemed...they are timed that way.
Old 05-07-08, 08:43 PM
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Originally Posted by waporvare
..quit using ethanol mix gas. ...
Ethanol is the worst. It really needs to be significantly cheaper than regular gas than what it is because of the poor fuel efficiency it gives you. I travel through Iowa at least once a year and their Ethanol is only ten cents cheaper than regular gas, but you get far, far less driving out of that one tank of Ethanol. It's not worth it and is a scam.
Old 05-07-08, 09:28 PM
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I think I read somewhere that around 60 mph is when your mpg really starts to take a dive. Seems like I recall it mentioning that as you go higher and higher speeds.. 70, 80, 90, your mpg gets disproportionately worse.

Fueleconomy.gov says:

As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas.

It also said that aggressive driving (speeding, rapid acceleration and breaking) can cost you up to 33 percent of your mpg on the highway.
Old 05-07-08, 09:58 PM
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Originally Posted by rmcarthur
I think I read somewhere that around 60 mph is when your mpg really starts to take a dive. Seems like I recall it mentioning that as you go higher and higher speeds.. 70, 80, 90, your mpg gets disproportionately worse.

Fueleconomy.gov says:

As a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.20 per gallon for gas.
I heard on the news a week or so ago that slowing down five miles per hour on the highway could save you fifty five cents per gallon. I thought that was really high...maybe they meant dropping from 75 to 55.

I am actually surprised we haven't heard more talk of the national speed limit being dropped back down to 55, or at least 60.

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