[MetroMPG]

Generally, coasting in N is more efficient because you get off the gas earlier, and coast further. The additional coasting duration offsets the tiny amount of fuel used idlng during the coast vs. fuel cut in deceleration fuel cut-off mode.

Letting off the gas in gear is good if you are (a) trying to slow down or (b) trying to hold your speed down a grade.

Unless coasting in N has me going too fast at the bottom of the hill, that's what I'll do.