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Gas Saving Tips

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191K views 402 replies 213 participants last post by  hamhead  
#1 ·
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#87 ·
jasongg06 said:
IMO it does, I do that once in awhile and i think it saves gas, but i've heard that it isn't that great for your transmission. I also know that when the hill ends, and you put it back in gear, the engine revs up, so you didnt' really save any gas.
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Actually its worse for gas mileage then if you left it in gear. When you are in gear your momentum going down the hill is turning the wheels and turning the crank, but your throttle plate is closed so you aren't using any gas. When you shift into neutral your car needs to keep the engine turning by using fuel.

Ps dumbest quote of the link is:
Avoid Excessive Idling

Idling gets 0 miles per gallon. Cars with larger engines typically waste more gas at idle than do cars with smaller engines.
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No kidding its 0 mpg cause your not going anywhere but thats not actual consumption.
 
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#8 ·
Put Manual Gearbox in Neutral to Save Gas?

NEMESIS_2006 said:
i always pop the gear in neutral on a downhill. does this have any benefit?
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NO. In neutral, the engine is at idle speed, meaning the throttle is OPEN. Leaving the tranny in the proper gear according to steepness of the grade means the throttle is CLOSED if your foot is completely off the gas pedal. That saves gas and is also a lot safer when the engine is doing some braking.

Going fast in neutral down a steep hill is bad news and UNSAFE :driving: ! There is lessened traction between your tire contact patches and the pavement, leaving everything up to you and your proper (hopefully) application of the brakes.

Another Tip: Don't use the Cruise Control in the rain, especially where there are likely to be puddles of water present. This can be dangerous when a wheel(s) under power hit a puddle and then a drier spot of pavement, resulting in an upset of the car's position, as in: from aquaplane to sudden braking, where Cruise Control becomes an enemy. The higher the speed, the greater the danger. (Will try to find this information on the Internet, where I first saw it, then post it here.) :banana-wa
 
#9 ·
Tybeedon said:
NO. In neutral, the engine is at idle speed, meaning the throttle is OPEN. Leaving the tranny in the proper gear according to steepness of the grade means the throttle is CLOSED if your foot is completely off the gas pedal. That saves gas and is also a lot safer when the engine is doing some braking.

Going fast in neutral down a steep hill is bad news and UNSAFE :driving: ! There is lessened traction between your tire contact patches and the pavement, leaving everything up to you and your proper (hopefully) application of the brakes.

Another Tip: Don't use the Cruise Control in the rain, especially where there are likely to be puddles of water present. This can be dangerous when a wheel(s) under power hit a puddle and then a drier spot of pavement, resulting in an upset of the car's position, as in: from aquaplane to sudden braking, where Cruise Control becomes an enemy. The higher the speed, the greater the danger. (Will try to find this information on the Internet, where I first saw it, then post it here.) :banana-wa
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Sorry but I still don't get how having the car in neutral is worse then having it in gear(for gas mileage). Could you or somebody else explain it differently? Thanks:)
 
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#10 ·
foolio_67 said:
Sorry but I still don't get how having the car in neutral is worse then having it in gear(for gas mileage). Could you or somebody else explain it differently? Thanks:)
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buy a vacuum gauge. install it. and check for yourself. when your in gear and off the gas the vacuum is greater then if your in neutral and idling. greater vacuum will equate to better gas mileage. theoritically i know this is correct, but because my current car is turbo with a gauge i see it first hand all the time.
 
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#11 ·
Tybeedon said:
NO.

Another Tip: Don't use the Cruise Control in the rain, especially where there are likely to be puddles of water present. This can be dangerous when a wheel(s) under power hit a puddle and then a drier spot of pavement, resulting in an upset of the car's position, as in: from aquaplane to sudden braking, where Cruise Control becomes an enemy. The higher the speed, the greater the danger. (Will try to find this information on the Internet, where I first saw it, then post it here.) :banana-wa
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sorry for double post. i had a friend who totalled his car doing that exact thing. cruise control was on, and he hit a puddle, tires slow down when aquaplaneing, and the computer actually hits the gas, who now your floating on water with the gas pegged to the floor, he went out of control and hit the center median and then rebounding across the road and hit a tree on the shoulder of the road.
 
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#13 ·
foolio_67 said:
Sorry but I still don't get how having the car in neutral is worse then [than] having it in gear(for gas mileage). Could you or somebody else explain it differently? Thanks:)
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Here's some more information that should help. :)

From a Post by “NeverNZ” – 07/25/06

“if you allow your car to slow you down, you do 2 things, first you are not wasting energy by using your brakes, and when the engine slows you it goes into a super lean mode (usually air fuel ratios above 17:1, sometimes far higher). this does no damage your engine, so don’t worry. However, if you put the car into neutral, the engine must maintain itself so it usually goes into a 14.7:1 air fuel ratio, therefore using more fuel while idling to a stop then [than] while engine breaking.”[braking].


From a post by “psyschack” - -7/30/06

(NOTE: His posts on driving for fuel economy are VERY interesting!)

Engine off, in netural [neutral] coast uses no fuel.
Engine on, in 5th gear coast is next best on fuel useage.
Engine on, in netural [neutral] is dead last in fuel savings.

Note: [xxxx] my ‘edits.’ (Tybeedon. 09/24/06)
 
#15 ·
Tybeedon said:
Here's some more information that should help. :)

From a Post by “NeverNZ” – 07/25/06

“if you allow your car to slow you down, you do 2 things, first you are not wasting energy by using your brakes, and when the engine slows you it goes into a super lean mode (usually air fuel ratios above 17:1, sometimes far higher). this does no damage your engine, so don’t worry. However, if you put the car into neutral, the engine must maintain itself so it usually goes into a 14.7:1 air fuel ratio, therefore using more fuel while idling to a stop then [than] while engine breaking.”[braking].


From a post by “psyschack” - -7/30/06

(NOTE: His posts on driving for fuel economy are VERY interesting!)

Engine off, in netural [neutral] coast uses no fuel.
Engine on, in 5th gear coast is next best on fuel useage.
Engine on, in netural [neutral] is dead last in fuel savings.

Note: [xxxx] my ‘edits.’ (Tybeedon. 09/24/06)
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Okay that makes sense, but I go down a pretty long hill (8-10minutes @ 110km/h) and I don't use my brakes until near the bottom. But at the bottom I put it into 6th to slow me down. Would this still be using more gas? Sorry if this was anwsered in your post, I just don't see it:xyxnervou
 
#16 ·
leakslikasieve said:
buy a vacuum gauge. install it. and check for yourself. when your in gear and off the gas the vacuum is greater then if your in neutral and idling. greater vacuum will equate to better gas mileage. theoritically i know this is correct, but because my current car is turbo with a gauge i see it first hand all the time.
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a litlel of topic. butt. where're you're frum! just wondrin cause u no alot bout vacuums.
 
#18 ·
Using non-anecdotal evidence, coasting down the hill from the Pahrump hills down into vegas (about 8 miles all down hill) using my OBDII port Scangauge II for accurate measurements of GPH (actual fuel consumption rates) and MPG, GPH of consumption at idle and coasting was 0.2GPH. Brakes are required to keep speeds under 75mph.

The same road, coasting in 6th resulted in a 0.3 to 0.4 GPH consumption rate. Additionally, active input was required to maintain speeds of 65 during portions of the downhill trip (less grade), increasing GPH consumption to between 0.5 and 0.7 for limited periods.

Net calculated MPG on the 'coast' from the Scangauge II was 270MPG average for the 8 mile 'coast'. Using the 6th gear coast with minimal input was just over 120MPG for the repeat run.

(Manual transmission, 2006 Civic Si)
 
#20 ·
Yes, MPG and GPH (gallons per hour) readings from the ScangaugeII show that coasting, out of gear, returns higher mileage and lower GPH consumption, by quite a fair margin. GPH consumption is 2X when in gear (6th) coasting than it is out of gear coasting.

Now, that is for my Si manual transmission. For an auto I have no idea what the returns will be. However, if you have access to an OBII 'real time' reader that supports GPH reading, MPG (based on speed and GPH), then anyone with one can easily check these figures on their own.
 
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