Manual or Automatic transmission..which do you prefer?

[COchief]

Originally Posted by DJ's left nut

This is wrong.

Manual transmissions don't actually do much (if anything) to save on gas anymore.

You got one point correct, including "this is wrong" in your bullshit post.

People never consider the EPA's mandatory driving style when getting MPG figures. Does the EPA hit neutral on a huge hill? When they see a red light a block ahead do they drop it into neutral? When driving a car with a lot of torque do they alter their shift points? Do they alter which gear they're in at certain speeds? The answer is no, they have to follow a strict set of guidelines. I drove a 2001 Maxima 5-speed that had a city MPG rating of 19, I was always near 30 just by dropping neutral when appropriate (live in CO, tons of huge hills, places I coast for miles) and by going to 5th at around 35mph since the engine had 217 of torque in a fairly small package. This is all I did, I actually am a pretty spirited driver, not a hyper-miling douche that takes an hour to get up to 50mph.

I currently have an auto Xterra, while I don't think I'd want it in a stick, there are so many situations where I would just pop it in neutral where the RPMs are 3k or more.

Also to the dumbasses that engine brake: You are burning a shitload of gas by keeping your RPMs up that high instead of idle and last time I checked brakes were about a hundred bucks. Why the hell would you wear out your engine/tranny over a part that costs a hundred bucks and if we are talking years of ownership, hundreds in gas. Simply stupid.

[DJ's left nut]

Originally Posted by COchief

You got one point correct, including "this is wrong" in your bullshit post.

People never consider the EPA's mandatory driving style when getting MPG figures. Does the EPA hit neutral on a huge hill? When they see a red light a block ahead do they drop it into neutral? When driving a car with a lot of torque do they alter their shift points? Do they alter which gear they're in at certain speeds? The answer is no, they have to follow a strict set of guidelines. I drove a 2001 Maxima 5-speed that had a city MPG rating of 19, I was always near 30 just by dropping neutral when appropriate (live in CO, tons of huge hills, places I coast for miles) and by going to 5th at around 35mph since the engine had 217 of torque in a fairly small package. This is all I did, I actually am a pretty spirited driver, not a hyper-miling douche that takes an hour to get up to 50mph.

I currently have an auto Xterra, while I don't think I'd want it in a stick, there are so many situations where I would just pop it in neutral where the RPMs are 3k or more.

Also to the dumbasses that engine brake: You are burning a shitload of gas by keeping your RPMs up that high instead of idle and last time I checked brakes were about a hundred bucks. Why the hell would you wear out your engine/tranny over a part that costs a hundred bucks and if we are talking years of ownership, hundreds in gas. Simply stupid.

Then your transmission is ****ed up.

My goddamn camaro doesn't idle above 800 and its 45 yrs old. If you're just rolling down a hill an automatic, the engine is going to be either idling or if you're on cruise it may downshift to keep you from accelerating past your target speed. It's not going to sit at 3k if you're not on the gas at all; it's going to coast down to idle speeds.

Oh, and you're wrong on the engine breaking thing - you don't use more gas when the RPMs come up during engine breaking. The RPMs are only rising due to the compression in the motor and the motor spinning down. It's not actually using any more fuel; it's the transmission turning the motor in the absence of fuel, rather than the motor turning the transmission. The RPMs come up because there's no place for the energy that the transmission is imparting on the motor to go (i.e. the engine compression) so the RPMs spin up and the compression finally peters the acceleration out. If you were actually feeding the motor fuel to create those RPMs, it wouldn't decelerate.

And while Radar and Hemi can speak to this more than I can, the last automatic I was fortunate enough to look at the guts of had some kind of slipping interlock in it where at lower RPMs it was barely engaged, so it's not like your breaks are having to work very hard to keep the car in place. At higher RPM the 'disks' in the transmission synch together and pull harder, so it's actually able to apply the power better. However, at low RPMs, the transmission isn't doing much work at all and as a consequence your brakes aren't doing much work.

And if you're spending a couple hundred dollars on brake pads - you're an idiot. If you had to replace the brake assembly altogether, it's because you were an idiot for a prolonged period of time, burned through your pads and ****ed up your rotors. That's when you start spending a couple hundred dollars. Brake Pads for your daily commuter are dirt cheap.

I reiterate, at it's very best, sitting in neutral at a stop light is going to do nothing more than save you a set of brake pads over the life of your car. Brake pads are cheap and easy to replace on your own. But hey, maybe you're right on those XTerras that idle at 3K.

To start out by calling my post bullshit and then excoriate people for burning fuel while engine breaking and then chirping about $200 brake pads is...interesting.

[alnorth]

Originally Posted by DJ's left nut

Oh, and you're wrong on the engine breaking thing - you don't use more gas when the RPMs come up during engine breaking. The RPMs are only rising due to the compression in the motor and the motor spinning down. It's not actually using any more fuel; it's the transmission turning the motor in the absence of fuel, rather than the motor turning the transmission. The RPMs come up because there's no place for the energy that the transmission is imparting on the motor to go (i.e. the engine compression) so the RPMs spin up and the compression finally peters the acceleration out. If you were actually feeding the motor fuel to create those RPMs, it wouldn't decelerate.

Yeah, this whole "coasting down hills in neutral saves gas" thing is apparently a myth. I used to believe it but I've read too many articles by car guys who knew what they were doing saying that the RPM difference in that situation was deceptive. Most of the insane hypermiler techniques that work don't depend on a manual. There might be a small benefit with idling in neutral at a stop.

I still prefer manuals, they are cheaper and more fun to drive, but most of the gas savings come from efficient shifting, not throwing it in neutral.

[Frosty]

Originally Posted by alnorth

I still prefer manuals, they are cheaper and more fun to drive, but most of the gas savings come from efficient shifting, not throwing it in neutral.

I have a Scan Gauge II, which is a diagnostic device that plugs into the OBDII port of the car and can give you real time feedback as you drive. One of the things you can get is instantaneous gas mileage.

I have found with several different cars that going from driving in gear to coasting in neutral at speed can make the mileage more than double (it would go up to around 60 - 70 mpg in the car I was testing). If you coast in gear, the mileage readout would say "9999", which basically meant I wasn't using any gas at all.

[alnorth]

Originally Posted by Frosty

I have a Scan Gauge II, which is a diagnostic device that plugs into the OBDII port of the car and can give you real time feedback as you drive. One of the things you can get is instantaneous gas mileage.

I have found with several different cars that going from driving in gear to coasting in neutral at speed can make the mileage more than double (it would go up to around 60 - 70 mpg in the car I was testing). If you coast in gear, the mileage readout would say "9999", which basically meant I wasn't using any gas at all.

It may be lying to you when coasting downhill in neutral.

http://www.popularmechanics.com/cars...l-fuel-economy

[Frosty]

Originally Posted by alnorth

It may be lying to you when coasting downhill in neutral.

http://www.popularmechanics.com/cars...l-fuel-economy

He's right that it's not exact but point is the large increase, not the exact amount.

[COchief]

Originally Posted by DJ's left nut

A pretty intelligent post, but still wrong.

Thanks for taking the time to make an intelligent reply.

My X doesn't idle at 3k, but it sure as shit will hold at least that when I am coming down the Mtn at a 6-8% grade (I told you I live in CO for a reason).

Are you really going to argue the point that if the same two cars are driving at 3500 rpm and one hits neutral, and the other slowly winds down that there will be no benefit of one engine being at 800 rpm vs 3500-3000-2500- for a period of time? The savings may be fairly minimal and the new trannys may help with this, but no way does that not burn more fuel. It may be semantics at this point, but even that point of releasing the gas vs an almost immediate drop to idle on auto vs manual will create a minimal savings. Remember you are arguing that if I have an s2000 at 9000 rpms and engine brake to a complete stop vs neutral it will be the exact same. Bullshit, you seem to be an intelligent individual, surely you can admit that even though the savings might be minute, a manual is definitely more efficient in this scenario.

I twice said pads were a hundred bucks, a hundred is pretty much standard for any shop to swap the front pads. You're really grasping with that. I have owned several performance vehicles that have been taken to the race track (a real road course, not a parking lot SCCA or circle track). I don't need brake repairs explained to me thank you very much.

[DJ's left nut]

Originally Posted by COchief

Thanks for taking the time to make an intelligent reply.

My X doesn't idle at 3k, but it sure as shit will hold at least that when I am coming down the Mtn at a 6-8% grade (I told you I live in CO for a reason).

Are you really going to argue the point that if the same two cars are driving at 3500 rpm and one hits neutral, and the other slowly winds down that there will be no benefit of one engine being at 800 rpm vs 3500-3000-2500- for a period of time? The savings may be fairly minimal and the new trannys may help with this, but no way does that not burn more fuel. It may be semantics at this point, but even that point of releasing the gas vs an almost immediate drop to idle on auto vs manual will create a minimal savings. Remember you are arguing that if I have an s2000 at 9000 rpms and engine brake to a complete stop vs neutral it will be the exact same. Bullshit, you seem to be an intelligent individual, surely you can admit that even though the savings might be minute, a manual is definitely more efficient in this scenario.

I twice said pads were a hundred bucks, a hundred is pretty much standard for any shop to swap the front pads. You're really grasping with that. I have owned several performance vehicles that have been taken to the race track (a real road course, not a parking lot SCCA or circle track). I don't need brake repairs explained to me thank you very much.

I'm saying that you're looking at 1 of 2 possibilities here.

1) The car isn't going to stay at 3500 rpm - it's going to simply idle down. Unless you're referring to the second it will take for the computer to realize that you're not accelerating (and if you were in overdrive, it shouldn't even take that long), there's no practical difference there. Take your foot off the pedal and your ECU will get to work keeping your mileage up - it's a cheap and easy way for Ford, etc... to improve fuel economy without drastically changing the motor design. Now, the other possibility is what I think you're referring two and thats when you're coasting down the hill (foot not on the gas) and your RPMs have come up to keep you from going 100 mph - in other words, 'involuntary' engine breaking.

2) Again, engine breaking does not have any impact on fuel economy. You may be right, on your steeper grades in Colorado your manual might be pushing 3500 going down the hill. But that's not a true 3500 - it's an idle speed that your transmission is running up to 3500. You're not using any more fuel there than you would if you stepped on the clutch. The fuel isn't what has you at 3500 - the wheels are.

The only difference in MPG would come from the fact that by engine breaking, you're reducing the distance you travel. If it takes you 5 seconds to stop, you will have used the exact same amount of fuel over those 5 seconds as you would have if you'd have just stepped on the clutch - but if you just step on the clutch you'll still be traveling, so your MPG goes up. Presuming, however, that you're stopping for a reason, you're just going to use your brakes to stop at the same point there's no actual travel gain.

[COchief]

Originally Posted by DJ's left nut

I'm saying that you're looking at 1 of 2 possibilities here.

1) The car isn't going to stay at 3500 rpm - it's going to simply idle down. Unless you're referring to the second it will take for the computer to realize that you're not accelerating (and if you were in overdrive, it shouldn't even take that long), there's no practical difference there. Take your foot off the pedal and your ECU will get to work keeping your mileage up - it's a cheap and easy way for Ford, etc... to improve fuel economy without drastically changing the motor design. Now, the other possibility is what I think you're referring two and thats when you're coasting down the hill (foot not on the gas) and your RPMs have come up to keep you from going 100 mph - in other words, 'involuntary' engine breaking.

2) Again, engine breaking does not have any impact on fuel economy. You may be right, on your steeper grades in Colorado your manual might be pushing 3500 going down the hill. But that's not a true 3500 - it's an idle speed that your transmission is running up to 3500. You're not using any more fuel there than you would if you stepped on the clutch. The fuel isn't what has you at 3500 - the wheels are.

The only difference in MPG would come from the fact that by engine breaking, you're reducing the distance you travel. If it takes you 5 seconds to stop, you will have used the exact same amount of fuel over those 5 seconds as you would have if you'd have just stepped on the clutch - but if you just step on the clutch you'll still be traveling, so your MPG goes up. Presuming, however, that you're stopping for a reason, you're just going to use your brakes to stop at the same point there's no actual travel gain.

There is a very surprising lack of information about this on the net, I read the popmechanics article which basically seemed to just say it's unsafe to be in neutral. I am surprised frankly, I know nobodies lives depend on this but I would think there would a definitive test done at some point.

I am basing most of this on my personal CO driving experiences which are not typical for sure, situations where I just hit neutral (exceeding the speed limit and coasting distance certainly come into play here) and coast for miles then the road evens out and I definitely would have had to get back on the gas earlier in an auto. This is mostly what drives me crazy about now being in an automatic here.

Oh, and I was basically talking a little point 1 and 2. I know #1 savings would be minuscule but they are savings none-the-less, #2 is interesting to me as if this actually held up that neutral at 800rpm would burn more fuel than the entire drivetrain spinning at high rpm. It makes sense until you engine brake an s2000 down a mountain road at 8000 rpm and realize it might be more efficient than sitting quietly at idle at 800 rpm. Know what I mean?

[Frosty]

Originally Posted by COchief

Also to the dumbasses that engine brake: You are burning a shitload of gas by keeping your RPMs up that high instead of idle and last time I checked brakes were about a hundred bucks. Why the hell would you wear out your engine/tranny over a part that costs a hundred bucks and if we are talking years of ownership, hundreds in gas. Simply stupid.

In a modern car, when you coast in gear (like to slow down or go down a hill), the ecu cuts out the fuel and the engine is driven only by the wheels (down to about 20 mph or so). I agree that it's harmful to slam the tranny down several gears to slow down in the hurry, but done right, it's a big gas savings.

I always try to slow down when I can by just letting off the gas and coasting down in gear. If I need to slow a little quicker, I might drop it a gear. Yeah, it bumps up the rpm's a little because of the lower gearing but you aren't using more gas. Coasting in neutral or with the clutch in saves fuel but is still uses some to maintain the idle plus you don't have the engine braking to maintain speed down a hill (I refuse to risk a speeding ticket in the name of mpg).

Also, you mention people that take forever to get to 50. People that do that are stupid. Any time you accelerate, your gas mileage sucks, so it makes sense to get up to an even speed as quickly as possible (within reason) to minimize the distance accelerating and maximize the distance driving at constant, even speed. About 60 - 70% throttle is the best trade-off.

For myself, I much prefer a manual. If you know what you are doing, it's much easier to manipulate the gas mileage with a manual over an automatic. I also like that you can engine brake down the steep mountain roads I drive sometimes rather than riding the brake all the way down. I also prefer to drive in snow with a manual. If I lived in a city, though, I would probably stick with an auto.


EDIT: DJ's Left Nut is a much faster typist than I.

[alnorth]

Originally Posted by Frosty

In a modern car, when you coast in gear (like to slow down or go down a hill), the ecu cuts out the fuel and the engine is driven only by the wheels (down to about 20 mph or so). I agree that it's harmful to slam the tranny down several gears to slow down in the hurry, but done right, it's a big gas savings.

I always try to slow down when I can by just letting off the gas and coasting down in gear. If I need to slow a little quicker, I might drop it a gear. Yeah, it bumps up the rpm's a little because of the lower gearing but you aren't using more gas. Coasting in neutral or with the clutch in saves fuel but is still uses some to maintain the idle plus you don't have the engine braking to maintain speed down a hill (I refuse to risk a speeding ticket in the name of mpg).

The way I understand it (and I'm not a car guy, this is the dumbed-down explanation I remember), the car always has to remain above a certain RPM to keep the engine going. When you coast downhill in neutral, the car has to burn gas all the way down. When you coast down in gear, as long as the car is above a certain RPM (unclear to me how the RPM happens if not burning fuel), the car doesn't have to use gas.

[Frosty]

Originally Posted by DJ's left nut

I don't know Brock well enough to call him a liar. Evidently you don't harbor such consternation.

I wasn't calling anyone a liar. I was just relating my experience.

FWIW, some hyper-milers do something called "pulse and glide". This is where you speed up to about 10 mph over the speed limit and then throw the car in neutral and coast until your speed drops to about 10 under. Rinse and repeat (it works but is a huge pain in the ass).

In more extreme cases, they will actually turn their cars off during the glide part and bump start it just by dropping the clutch while in gear. This is in modern cars, so it doesn't seem like there is any issue there.

Originally Posted by COchief

Are you really going to argue the point that if the same two cars are driving at 3500 rpm and one hits neutral, and the other slowly winds down that there will be no benefit of one engine being at 800 rpm vs 3500-3000-2500- for a period of time? The savings may be fairly minimal and the new trannys may help with this, but no way does that not burn more fuel.

You use no fuel if you stay in gear. The rub, though, is that you can coast farther in neutral than you can in gear so you have to take that into consideration.

Originally Posted by alnorth

The way I understand it (and I'm not a car guy, this is the dumbed-down explanation I remember), the car always has to remain above a certain RPM to keep the engine going. When you coast downhill in neutral, the car has to burn gas all the way down. When you coast down in gear, as long as the car is above a certain RPM (unclear to me how the RPM happens if not burning fuel), the car doesn't have to use gas.

That's right. I may have misunderstood your point. I thought you meant coasting in neutral gives you better mileage (over just driving) is a myth.

[alnorth]

Originally Posted by Frosty

That's right. I may have misunderstood your point. I thought you meant coasting in neutral gives you better mileage (over just driving) is a myth.

I'm saying that the idea that coasting in neutral saves gas over coasting in gear, is a myth. You should coast in gear.

[Frosty]

Originally Posted by alnorth

I'm saying that the idea that coasting in neutral saves gas over coasting in gear, is a myth. You should coast in gear.

Agreed to a point. As mentioned, you can coast much farther in neutral than you can in gear so you have to consider that. I have some hills that I can't maintain speed in gear but can in neutral so I save gas over slowing down in gear and then having to accelerate back up to speed or just driving normally. You have to figure out when each method is best.