Pulse and Glide with the engine running?

[Geonerd]

I think the original idea might be made to work, although I doubt the FE gains would be impressive. Instead of a full DFCO throttle chop, apply just enough gas to roughly offset the engine drag. Your car will slow at a rate close to it's coast down deceleration. During this glide phase, you'll be using a lot more gas than at idle, but less than you would at steady-state.

Overall efficiency would depend on the battle between the peak BSFC pulse, and the low efficiency (but low power) semi-powered coast period. I'm guessing that FE at highway speeds would be slightly improved over steady-state.

At slower speeds, where you can gear the engine to run at low revs, this technique should work pretty well. Engine drag is vastly reduced and you're probably not using a whole lot more gas than at idle.

(A slipper clutch would sure be nice, eh?)

-Moo