Before computer controlled fuel injection drifting in neutral definitely where possible reduced gas consumption.

But drifting in neutral with a computer controlled fuel injected engine might actually increase fuel consumption . If the computer detects that the throttle pedal is not depressed and the engine rotation rate is above the minimum for reliable operation the computer can cut fuel off to the engine entirely, thereby relying on the cars forward momentum to keep the engine alive without the need for any fuel. If engine RPM's drop below a certain value the computer can reenable the flow of gasoline before the engine stalls or stumbles.

I believe, but am not sure, that this is what modern computer controlled fuel injection systems do.

As an aside, I like driving stick shift automobiles. I generally get about 10% better mileage than the EPA rating for the car for highway driving. I not only don't mind shifting in traffic, I enjoy the fact that it gives me something to do to help reduce the tedium. I think the fact that the US mostly drives automatics is more the result of a tremendously successful advertising campaign that convinced generations of Americans that it is difficult or tedious regardless of the truth of the matter. The automobile manufacturers were motivated to do this to benefit from increased profits resulting from the sale of unnecessary automatic transmissions.

I've noticed that in my 2006 Corolla idling in Neutral has the engine at a slightly higher RPM than in 'Park'.