[Gasoline Fumes]

Engine off in neutral is the true winner, but I'll use all three at different times. DFCO if I need to slow down or control speed, and idling in neutral if I'm trying to keep the heater output up in really cold weather.

Since idle consumption is fairly consistent, the faster you're going, the better idling in neutral gets. DFCO might be better at lower speeds. Drive a consistent route and have a way to measure trip MPG? Try both ways!