Pulse and Glide with the engine running?

[theholycow]

Originally Posted by DracoFelis

That's clearly a YMMV thing. Yes, you don't save as much fuel as with EOC

I wasn't comparing to EOC, though.

but in at least some cars P&G using DFCO does save fuel.

I suppose it's possible for some cars to do better with P&DFCO than with P&G (engine on, trans in neutral), but I suspect it would be rare. The losses with P&DFCO would have to be very abnormally small, and the losses with idling would have to be abnormally high.

Don't forget: Any work you do while in neutral, you do while in DFCO; but there's additional work that needs to be done in DFCO -- extra engine revolutions.

I've noticed in my CRX, for example, that my best fuel tanks are often when I'm in very light traffic and can therefore do P&G DFCO.

I suspect that you would get the same or better FE with engine-on P&G under that light traffic condition than with P&DFCO.

A few line items...

OTOH it really depends upon your level of "engine braking"

Definitely. This is affected by engine size, gearing, and friction losses.

1) Since the engine is connected during DFCO (but not during a neutral coast), extra good engine lubrication [...]
2) And the transmission is also connected during DFCO, so lowing losses in the transmission

That would help with those friction losses.

4) Since the alternator is connected during DFCO, saving electricity (LED lights, turning off accessories when not needed, etc) helps lower the alternator drag you experience with DFCO (again, lowing the slowdown hit of DFCO relative to a neutral coast).

The electricity is not free. It's the same amount of electricity, just made at different times from different sources depending on which technique you use. Therefore, saving electricity makes approximately the same improvement whether you prefer to P&DFCO, P&G, or P&EOC. If you don't run the alternator now you'll have to run it later.

NOTE: For safety reasons, I generally like DFCO when I'm in traffic, over EOC.

Safety first. If you feel that you might be sacrificing safety to EOC or neutral coast, then it doesn't matter how much gas you're saving.