...Is it safe? Or damage waiting to happen? Our new station finally opened and its changed my commute to where I have to cross a mountain now..its about 9 miles across it so I wanna say about 4.5 miles is down hill. Goes up to about 52xx ft from about 3xxx feet above sea level so its got some steep areas. Lately ive just been puttin it nuetral and letting it coast down to save a bit on fuel, is this bad???
coasting downhill in neutral...
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darien87
Member
I don't know if you're actually saving much fuel that way. When you're idling, the car's mixture is at it's richest, so you're actually burning more fuel. That's one of the reasons why your gas mileage during city driving is so bad. You're wasting a ton of gas when you're sitting at a stop light.
If I'm at a light that I know I'm going to be waiting for a minute or so, I go ahead and shut off my engine. I save a little gas, and I'm doing my part for the environment.
If I'm at a light that I know I'm going to be waiting for a minute or so, I go ahead and shut off my engine. I save a little gas, and I'm doing my part for the environment.
darien87
Member
I'm not sure at what speed the amount of fuel burned becomes less than at idle. It could be that coasting instead of going 70 will save fuel. Hopefully someone that knows more about this will chime in.
stangdude2000
Founding Member
I always read in all the car magazines that all modern cars can recognize coasting and nearly completely shut down fuel flow, making it more efficient to stay in gear. They recommend doing this, and they don't mention why it might damage the engine or transmission.
As far as damage, I'm not sure, but for gas mileage, here is an easy way to tell. Day 1, coast at the speed limit for say 10 min or so. Reset your average gas mileage counter. Day 2, leave it in gear starting at the same spot for the same distance. Again, reset the mileage before you start. Let us know the results!
As far as damage, I'm not sure, but for gas mileage, here is an easy way to tell. Day 1, coast at the speed limit for say 10 min or so. Reset your average gas mileage counter. Day 2, leave it in gear starting at the same spot for the same distance. Again, reset the mileage before you start. Let us know the results!
walter
Founding Member
Not to mention (if you're 5speed) that depending on the situation you may be placing yourself at risk if you release the clutch too suddenly or do so over dust/dirt the rear might lock and send you spinning.
imfamousjim
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- Mar 12, 2009
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pfft, with a decline like that i'd just shut the car off... your moving fast enough so steering is easy, and the brake pedal would be a good morning workout. haha
but what do i know, i'm in good ol flat new jersey
but what do i know, i'm in good ol flat new jersey
Id try shutting the car off but its got some curves worthy of the best coner carvers...itll easily hitt 100+ if i dont use the brakes (which i keep it at around 80). Its a 5spd btw...and it doesnt have the fancy features of the iup (youd think the cs would have it standard)...I think i will leave it in gear though because it is taking its toll on my brakes lol especially with 20's
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walter
Founding Member
Smart move.
You don't want to end up at the bottom of the hill with fried brakes. These cars have sucky brakes period.
You don't want to end up at the bottom of the hill with fried brakes. These cars have sucky brakes period.
cusp
Member
I don't usually do that because I like to use engine braking to check the speed on those descents. Also I have read that with fuel injected engines, they shut off the fuel anyway where as in Neutral they have to keep the engine turning over. You make the trip every day, so try the test some one mentioned. Let us know cause I am guessing here as well.
NotQuik
Founding Member
i'd monitor your fuel mileage going both ways. I live in florida but coast often to stop lights and it actually helps with fuel mileage technically. If your coast a mile it's still registering the mileage on your vehicle in turn showing better MPG. I was in tenn. over x-mas and coasted 14.5 miles down a mountain in my f150 but them brakes were HOT and receiving major brake fade towards the end, so something else to keep in mind...then again the f150 gets more momentum than the mustang due to weight.
I just wanted to resurrect this thread and share my 2c. I have been making a conscious effort to try and drive under 2k rpm as I heard that was a sweet spot for good fuel economy.
I'm driving an 03 so I don't' have a gas mileage indicator. But lately I have been resetting the trip odometer each time I fill up and then logging my mileage/refill qty in a spread sheet to figure out my mpg. During the last 4 fill ups I have averaged 20.08 mpg with my best at 20.958 mpg (I still had half a gallon before filling up). I'll be filling up again in the morning and I expect to be close too 21 again.
My commute distance is only 12 miles (but sometimes a little extra city driving after work to get some fast food)
Basically the last few weeks my driving practices have been as follows. Stay under 2k rpm (even when getting on the freeway). Sometimes I can't help it cause one on ramp is a steep incline but usually I'm barely over for just a short time.
Coast down hill
Coast exiting freeway (typically until stop sign/light)
Coast to stop signs/lights.
I encounter several hills during my commute and of course on the return trip too. When school is out I can typically get to work in about 12 minutes so that's a 60 mph average. When school is in it takes about 25 minutes so that's about 28.8 mph if my math is right.
So with my main goal being low rpms I just figured low rpm = low fuel consumption. Prior to reading this topic I never considered fuel injection would shut off during coasting. All I knew was the RPM's would would stay around 1500 vs about 900 when coasting.
Now, I did know that keeping it in drive provides a slight breaking affect but breaking doesn't help fuel efficiency because you lose a lot of momentum and therefore cannot coast as long. My max coasting speed is about 75 and I don't break that much.
I am curious to know if there is any article that documents a transmission wearing out much faster because of this. I've never heard it from anyone with any mechanical experience and usually they heard it from someone else.
I'm driving an 03 so I don't' have a gas mileage indicator. But lately I have been resetting the trip odometer each time I fill up and then logging my mileage/refill qty in a spread sheet to figure out my mpg. During the last 4 fill ups I have averaged 20.08 mpg with my best at 20.958 mpg (I still had half a gallon before filling up). I'll be filling up again in the morning and I expect to be close too 21 again.
My commute distance is only 12 miles (but sometimes a little extra city driving after work to get some fast food)
Basically the last few weeks my driving practices have been as follows. Stay under 2k rpm (even when getting on the freeway). Sometimes I can't help it cause one on ramp is a steep incline but usually I'm barely over for just a short time.
Coast down hill
Coast exiting freeway (typically until stop sign/light)
Coast to stop signs/lights.
I encounter several hills during my commute and of course on the return trip too. When school is out I can typically get to work in about 12 minutes so that's a 60 mph average. When school is in it takes about 25 minutes so that's about 28.8 mph if my math is right.
So with my main goal being low rpms I just figured low rpm = low fuel consumption. Prior to reading this topic I never considered fuel injection would shut off during coasting. All I knew was the RPM's would would stay around 1500 vs about 900 when coasting.
Now, I did know that keeping it in drive provides a slight breaking affect but breaking doesn't help fuel efficiency because you lose a lot of momentum and therefore cannot coast as long. My max coasting speed is about 75 and I don't break that much.
I am curious to know if there is any article that documents a transmission wearing out much faster because of this. I've never heard it from anyone with any mechanical experience and usually they heard it from someone else.
imfamousjim
Member
- Mar 12, 2009
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- 7
if you never pass 2000 rpm, buying a prius would help your fuel consumption and performance should be about the same.
Ken04
New Member
I've heard this too, that on decel your fuel injectors are basically closed unlike at idle.
69mach1-409
Member
..but coasting in gear also causes a drag that coast in N doesn't. I wonder where the break even point is on the drag of being in gear vs coasting in N.
I can't really test anything here in South Jersey... I think our highest elevation is 15'. LOL
I can't really test anything here in South Jersey... I think our highest elevation is 15'. LOL
Hey everyone. Just wanted to report back here with my fuel log.
One important thing to realize is the MPG is based on the fuel from the last fill up because you can't know your rate of consumption until you, you know... consume it. hehe.
I have logged all pertinent info, date of fuel up, mileage since last fill up, volume fille, name of station, fill cost, cost per gallon etc.
What I find interesting is I have achieved the best MPG when filling up at chevron. And keep in mind I always fill with regular no matter where I go.
And as you can see, chevron always costs about 10 cents more per gallon. So in a full tank of 14 gallons, I am paying $1.40 more for chevron than other places...BUT I get half a mile more per gallon efficiency which is like getting like 1/3 of a gallon saved for if that makes sense. Or tell me if my logic is flawed.
One thing I hope to see more clearly is how much traffic really plays a role in fuel economy for me. As I mentioned I have a pretty short commute but I do no i'm on the road longer when school is in. So hopefully this summer I'll have a good few months to fill up at a variety of stations and get more consistent results.
Just in case the attachment messed up when I replied here's another link.
One important thing to realize is the MPG is based on the fuel from the last fill up because you can't know your rate of consumption until you, you know... consume it. hehe.
I have logged all pertinent info, date of fuel up, mileage since last fill up, volume fille, name of station, fill cost, cost per gallon etc.
What I find interesting is I have achieved the best MPG when filling up at chevron. And keep in mind I always fill with regular no matter where I go.
And as you can see, chevron always costs about 10 cents more per gallon. So in a full tank of 14 gallons, I am paying $1.40 more for chevron than other places...BUT I get half a mile more per gallon efficiency which is like getting like 1/3 of a gallon saved for if that makes sense. Or tell me if my logic is flawed.
One thing I hope to see more clearly is how much traffic really plays a role in fuel economy for me. As I mentioned I have a pretty short commute but I do no i'm on the road longer when school is in. So hopefully this summer I'll have a good few months to fill up at a variety of stations and get more consistent results.
Just in case the attachment messed up when I replied here's another link.
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