I'm a Chrysler tech, there's a actually article on my dealer connect about the new suspension designs..

 

I thought staying in gear downhill would be better than coasting in neutral. In neutral it uses fuel to keep the engine running, I.e. Idle. In gear the engine is kept turning using no fuel.

 

As long as the engine is running it's burning fuel. If there were zero fuel, there would be zero combustion. This means the motor would not be running. If you can figure out a way to get the jeep to drive down the road without the engine running, besides being towed or in neutral with the engine off coasting.. I WANT TO KNOW!!!

 

What is the dealer connect you refer to?

 

As bombout800 stated, when the engine is running, it is always going to burn fuel. With that said, when you coast down a hill in gear, you will notice the tach increasing meaning the engine is turning faster therefore the pistons are going up and down at an increased rate (rounds per minute: RPM) which draws in more air and fuel to create the internal combustion. If you press in the clutch while traveling down a hill, you will notice the tach or RPM drop and as you stated "idle." Yes, the motor is still using fuel to stay running but not nearly as much as leaving the vehicle in gear traveling down said hill.

 

I still think I am correct here are some quotes:

When coasting with the engine running and manual transmission in neutral, or clutch depressed, there will still be some fuel consumption due to the engine needing to maintain idle engine speed. While coasting with the engine running and the transmission in gear, most cars' engine control unit with fuel injection will cut off fuel supply, and the engine will continue running, being driven by the wheels. Compared to coasting in neutral, this has an increased drag, but has the added safety benefit of being able to react in any sudden change in a potential dangerous traffic situation, and being in the right gear when acceleration is required

And another from fuelacademy.com: Driving down hill in neutral (free wheeling) you will use some fuel. When you drive down hill in gear (the safest gear under the circumstances) in a modern day car you will use NO fuel whatsoever

And one from popular mechanics: Almost all vehicles show a pulse width of zero when coasting while in gear. Zero, as in there is no fuel injected at all. Yes, the engine is turning over, the pistons are going up and down, the water pump, alternator and a/c compressor are working, so technically you can say the engine is running, sort of. But it's not consuming any fuel. And that goes for automatic or manuals.

Pulse width for fuel injectors...

http://en.m.wikipedia.org/wiki/Energy-efficient_driving

http://www.fuelacademy.com/taylors_tips_21to30.html

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

 

^ Popcorn who knew a Jeep could run without burning gas!?!

 

@ castlerockjeep, I definitely agree with you after reading the article links you have. I was gathering my information from my jeeps "avg eco." Thank you for the clarification.

 

With that said, I would presume down shifting before a stop also helps fuel economy vs. pushing in the clutch and breaking.

 

My 3.8L/auto definitely shuts off the fuel going down hill when my foot is off the gas pedal.
The injector pulse width goes to zero; I get additional engine braking to prevent a gain in speed; and I can feel it when the injectors turn on at the bottom of the hill.