So says Popular Mechanics:
Interesting, I didn't know about the injectors shutting off when coasting in gear. With a carbureted engine, you would save some, but it is much harder on the brakes. I had a motor home that wouldn't lock in low, it would just jump to
2nd no matter the selector position. That was downright scary in Colorado brake fade was a certainty, not so much if, as when. As soon as I got to the flat lands I pulled the valve body and put one in from a 4wd truck. then it would stay where you put it, and descending grades was almost fun.On the other hand, with a standard trans, always coast into red lights on level ground. I'm going to idle in neutral with the clutch out, waiting for the light, so it sets up the maneuver nicely, it saves the throw out bearing.
I dont buy it, it isnt a gasolene consumption issue, when coasting in gear the engine is not moving at idle speed, the extra rpms are a drag on the transmission and lower mpg, the trans also has more drag being in gear. He is only thinking gasolene not drivetrain friction loss.
The guy is an idiot.
My parents owned a 70s Saab Monte Carlo with asperated V4 and positive engagement. When the car was not accelerating, the transmission disengaged entirely from the engine. It could also be switched to normal operation, but got better mileage with the tranny in constant disengaged mode, though it took some getting used to. It also had excellent disc brakes, obviously. I understand there were other cars with this feature. I ended up owning it for awhile. Great car.
nb
=3D=3D Coasting in neutral has to be one of the more stupid ideas circulating. You are essentially losing control of your vehicle in a sense and the transmission has no effect on braking and brakes will have to be used more. For acceleration, one has to engage the clutch and shift to the desired gear or in an automatic shift to the desired "mode". Why complicate one's existence? The saving is insignificant at best. I doubt that any great number of drivers would even contemplate such a stupid maneuver.
=3D=3D
I like the sound of my engine so whenever possible I put it in neutral and red line the tach.
He's assuming at least two things that are wrong: "a rule of thumb for idling fuel consumption is 1 gph"
That is not a rule of thumb, and idling a CAT C-15 set up for 475 hp. doesn't burn anywhere near 1 gph.
Still, coasting in neutral is a bad idea for the control issues alone. -----
- gpsman
That doesn't make any sense at all. If the injectors are delivering no fuel, none of that matters. The engine isn't consuming any fuel, but the vehicle is still moving forward: mpg is infinite.
According to the article, coasting in neutral burns gas, coasting in gear doesn't. If that's correct, then OBVIOUSLY you use less fuel coasting in gear.
That was one of Saab's two-strokes, right? The thing with two-strokes is the accelerator doesn't just feed the fuel, it feeds the lubricant. Try to engine brake with one and you get high revs with no lube. Then pretty soon you get no revs at all.
See
LOL
=3D=3D Ain't that the truth... =3D=3D
No. The two stroke was a three cylinder. The V-4's were four cycle.
No it's not so obvious..Lets say there is a gradual 1 mile down hill.
Lets say coasting in gear uses no gas but due to the engine drag you can coast for only 1/2 mile then you need to use the gas to go the next 1/2 mile.
OR if you coast in neutral and use a small amount of gas to keep the engine turning, but no drag on the car you can coast 1 mile?
Which uses less gas to cover that mile?
Not so obvious..
But I think coasting in neutral is a bad idea for many reasons including saftey, and I'd rather pay a few pennies more for gas and have less wear and tear on a $2000 transmission.
Mark
Ah! thanks.
Chip C
The two-strokes were 3-cylinder inlines. The 96 phased in the Ford Taunus V4 in 1967 and 1968. It didn't need freewheel but Saab kept it.
I'm curious about the author's assertion that a car won't corner without drag or thrust from the engine. If that were true of Saabs, the company would have gotten rid of freewheel. I drove a 96 until 1984. I didn't lock out freewheel because I didn't notice any problem.
Most newer cars the OBDII keeps the RPMs up according to the speed, not the pedal. I can shift into neutral while driving say at 35mph and my RPMs won't drop to idle but rather slowly decrease with the speed of the vehicle. I guess this is to limit drive train noise from slack.
Shut the engine off at the same time to save even more. If you are going in a straight line the lack of power steering and brakes shouldn't bother you.
Then you cant Rev it and make it sound good
Coasting the motor idles right, even coasting at 70 downhill the motor is only getting gas to idle, but in gear at 70 it wont be 6-700 rpm it will be maybe 1400 rpm, the increase is drag through the drivetrain not gasolene.
They both use the same gas, in gear or out, with foot of the accelerator its in idle mode, just enough gas to run the motor.
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