Originally Posted by dragonballz
At idle, in neutral it is using less fuel than if he kept it in drive. It is 0.9 Liters per hour in neutral. 1.15 Liters per hour in Drive.
That's 8.43 Ounces per hour.
15 hours of idling to make a difference of 1 gallon.
5 hour trip at 30mph avg, 1 hour of that is idling.
Baseline 25mpg (normal driving, leave trans in drive)
150/25 = 6 gallons used
Same trip, shift to neutral, 5.934 gallons used
150/5.934 = 25.28mpg
Like I said... no impact on fuel economy. That is statistically insignificant, and is assuming a full hour of idling on a 5 hour trip of 150 miles.