[ever_green]

So I read increased timing and less fuel can help you save a lot of gas. My Subaru recently was tuned mostly for power due to additional powertrain modifications such as 11:1 pistons, bigger camshafts, ported valves and headers. This tune included much richer fuel ratios, higher timing under load and less under cruising due to disabled EGR and disabled fuelcutoff/overrun. My 4000 km average for trip from work to home before my economy map was 13 L/100km. Therefore I have now decided to tune for economy for this summer since I only drive to work in downtown area and back home. I think it's possible to run full lean 14.7:1 on this car without issues below 3000 RPM.

My first problem is whether I should enable EGR? I know EGR should allow me to run a lot more timing during cruising, but i'm not sure if that extra timing will make up for loss of oxygen content introduced to the combustion chamber?

Second problem is whether running 14.7:1 really makes much of a difference compared to high 13s considering that I will probably lose torque and possibly have to reduce timing as well?

Finally overrun fueling or DFCO, will this help? I notice with DFCO car generates strong engine braking where as in without it the car rolls down the hill with no resistance at 650 RPM.

I'm wondering if this is worth the effort. thanks.