Keep Gas Prices From Bankrupting You This season

[pandacover]

Conserve Fuel

Mind the basics. Go easier on the gas pedal and shun your A/C if you're just driving around town.
Work with your car, not against it. Clean the junk out of the trunk, let off the accelerator earlier when approaching a stop, speed up before hills to make the climb easier, and use the cruise control more.
Keep those RPMs low. Learn how to skip gears if you've got a stick-shift, avoid engine braking, and reacquaint yourself with Neutral (it's not just for towing).
Take care of your car. Tire pressure, spark plugs, air filters, oil—they all make a huge difference.
Pick the right station. If you can save a whole dollar by going to a different station in town, by all means do it. If the difference is just a few cents, you're probably not saving much by driving several miles to the cheaper station.
Don't drive if it isn't necessary. Public transportation can be a wondrous thing for your wallet, and walking or riding a bike are even better if your destination is nearby.

[Motorcycle Forum]

[JmalB]

Most modern cages using engine braking is more fuel efficient than coasting down in neutral. Slowing down in gear means there is no fuel being delivered to the motor. Slowing down in neutral means it has to add fuel to keep running.

Putting an automatic in neutral at a stop will, however, reduce load on the engine and consequently fuel consumption.

[inspiron]

Avoid engine braking? I don't think so. First off, as Jmal said, modern cars shut off the fuel flow to the engine as soon as the computer detects that the wheels are rolling faster than the engine is turning, making engine braking more efficient from an ecological and economical standpoint.

Further, my fire department training has taught me to use engine braking as much as possible - engine braking is essentially a zero-cost action, whereas replacing brake pads is very expensive (on a 14-ton fire truck). That's why, as a truck driver, you try to engine brake as much as possible.

The price difference between stations depends a lot upon where you live. In my area, the price of fuel varies about 3 to 4 cents per liter, so I can save about 1.20 to 1.60 per tank. However, if I drive over the border into Germany, the price of diesel is about 18 cents per liter cheaper, so I can save about 7.20 per tank. As I am driving into Germany several times each week, this would be the most economic solution (for me).

[Easy Rider]

Slowing down in gear means there is no fuel being delivered to the motor.

What leads you to believe that ?
It is NOT true.

AND....modern automatic transmission vehicles, with no rear pump in the transmission, provide very little drag when coasting in gear......down to the point where the transmission starts downshifting, that is.

Any time the engine is "running" it is using some fuel.

Diesel "jack brakes" may be an exception.

[QZephyr]

OK everybody, panda did it again. This is an article from lifehacker.com. The posting title was changed from Summer to season. I'm not sure panda has actually posted a real thread or just a copy/paste thread.

[JmalB]

What leads you to believe that ?
It is NOT true.

AND....modern automatic transmission vehicles, with no rear pump in the transmission, provide very little drag when coasting in gear......down to the point where the transmission starts downshifting, that is.

Any time the engine is "running" it is using some fuel.

Diesel "jack brakes" may be an exception.

How is what I said not true and what Inspiron confirmed is? Maybe I confused the issue by not mentioning I meant with manual transmissions. Modern fuel injected manual transmission cars will shut off the fuel when coasting down in gear. Momentum keeps the engine running.

And I thought it was called a jake brake.

[Easy Rider]

Modern fuel injected manual transmission cars will shut off the fuel when coasting down in gear.

I don't believe that is true either......as an engine receiving NO fuel would pose a LARGE drag and turning the fuel back on would probably make a rather pronounced jerk.
Unless it's coupled with electronic valves that can be left open, it would be similar to shutting off the ignition while going down the road.

The question remains: What leads you to believe that ?

[inspiron]

The on-board computer in my car (Audi A3, 2.0 TDI, with a 6-speed manual transmission) shows a fuel consumption of 0.0 when I'm coasting down a hill using the engine to slow the car. As far as I know, Audi's computer does shut off the fuel flow to the engine when engine braking. I'll need some time to find an authoritative reference, though.

[Easy Rider]

The on-board computer in my car (Audi A3, 2.0 TDI, with a 6-speed manual transmission) shows a fuel consumption of 0.0 when I'm coasting down a hill using the engine to slow the car.

Does it also have variable valve timing ?

The Audi may not be a good example of cars in general, as many of them seem to have "advanced" engineering.

I don't dispute that there is a very tiny amount of fuel used but just not none.

And I don't contend that it is not possible.......but that it wouldn't be worth the trouble in your average car.

[otdriver]

The on-board computer in my car (Audi A3, 2.0 TDI, with a 6-speed manual transmission) shows a fuel consumption of 0.0 when I'm coasting down a hill using the engine to slow the car. As far as I know, Audi's computer does shut off the fuel flow to the engine when engine braking. I'll need some time to find an authoritative reference, though.

That doesn't mean that that the fuel is shut off, if that would be case the engine would also shut off, then you'd loose power steering assist and power braking assist. If you start the engine and leave the trans in PARK or NEUTRAL and sit there, the computer most likely indicates 0.0 fuel consumption but the engine is in fact using some fuel, the same thing applies on decellerating conditions.

[intimid8er]

Granted...I was already practicing everything the OP stated...., and having a real go of it to. Tried to out do myself every week. I served to nothing but foul my Mustang up fairly well. All for an extra gallon or two. The check engine light came on, and it started idling rough.

I was using momentum, and grades to stay off the gas as much as possible. Short shifting, skipping gears. It damn well choked the car out. I went back to running it to the upper ranges of each gear, and make a smooth, concise shift. Not flooring it mind you, just getting the most out of each gear. The difference in consumption per week is minimal. The best so far has been a gallon. Every other has been less. The idle is back to normal and the car runs like it should again.

[JmalB]

I don't believe that is true either......as an engine receiving NO fuel would pose a LARGE drag and turning the fuel back on would probably make a rather pronounced jerk.
Unless it's coupled with electronic valves that can be left open, it would be similar to shutting off the ignition while going down the road.

The question remains: What leads you to believe that ?

That doesn't mean that that the fuel is shut off, if that would be case the engine would also shut off, then you'd loose power steering assist and power braking assist. If you start the engine and leave the trans in PARK or NEUTRAL and sit there, the computer most likely indicates 0.0 fuel consumption but the engine is in fact using some fuel, the same thing applies on decellerating conditions.

The drag is part of the bonus. Probably? Similar but not as extreme. We're talking about cutting fuel, not completely removing power. Momentum (fly wheel effect?) keeps the engine spinning. Which runs the altenator, water pump, power steering pump and other accesorries.

The easiest way to prove this would be to have a car with one of those fancy mpg displays. But alas all of mine are more spartan.

When you are decelerating you are using/needing less fuel. If the engine slowing down wasn't producing drag the car wouldn't slow down as much. Example: Coasting in gear vs coasting in neutral. Which slows the car down faster?

What leads me to believe this is reasoning. What I understand of the mechanics/physics of it all allows me to draw the logical conclusion that "yes, I see how that could work".

Engine braking - Wikipedia, the free encyclopedia
The section under legal implications.
Fuel economy-maximizing behaviors - Wikipedia, the free encyclopedia
Granted it is Wikipedia and there is no valid citation given, but it says basically the same thing I'm trying to.

[300winmag]

I just switched my on board computer to show the L/KM usage so next time I'm engine braking I will see what numbers I get. I know when I'm at a red light it maxes out the display(over 15 L/KM).

[Easy Rider]

We're talking about cutting fuel, not completely removing power.

The easiest way to prove this would be to have a car with one of those fancy mpg displays.

By definition, removing the fuel IS removing the "power".

With a manual transmission, the kenetic energy would keep the engine turning for a while.
With a modern automatic, no fuel = stops turning.

And without knowing exactly how the MPG display arrives at it's numbers, that means virtually nothing.
Every one I've ever seen shows 0.0 when stopped and some incredibly high number when coasting.

On a kind of related note: Saw a report on TV a few days ago about a couple of "red neck engineers" who claimed an energy saving breakthrough for refigerated trucks by powering the cooling compressor from the truck wheels instead of from it's own seperate little diesel engine. The report seemed to be saying that they were amazed that nobody had realized that there was "fee energy" there to be used when the truck was slowing down.

All a bunch of BS. It only saves you anything from the "free energy" when it is used as extra braking when the truck comes to a complete stop.
Other times, the engine has to work harder to regain the lost speed.
Nothing is free, energy wise.......and the real advantage of their method is that the BIG truck engine is more efficient at producing a little bit of extra energy than the seperate little engine is in the refigeration unit.

This is not anything new as real engineers have known it for a long time.
The extra hardware necessary to make it work is only worth the investment when the price of diesel fuel goes WAY up.........as the trailer still has to have it's own motor for when the truck is OFF.

[intimid8er]

What's anybody's take on the gizmos with rods in water that get hooked to the battery and the carb/fuel injection system?