I'm shooting for 40mpg with my Escort when it is back together, then 50mpg with additional tricks and aero refinements.
Then I'm shooting for 30mpg with my minivan with aero and tweaks before I rebuild the spare motor, then 40mpg after, possible potential of 50mpg highway with displacement on demand.
Then I'll start messing with HHO cells and try and push the escort to 65-70 and the van to 60. Then there's still thermal efficiency gains to be won, done properly it could double up everything else, but one is stuck with compromising around what is there.
Then if that's not enough for me I'll convert them both to standards and start EOCing....
But mostly these plans are aimed at arranging things such that they can get high mpg when daily driven by my wife and remain a practical vehicle.
Maybe if I get bored with them when they're in the 50+ range I'll buy a 91-96 Escort* 5 speed hatch and do a no compromise 100mpg+ project car. (Because they're lots cheaper than hondas, fairly aerodynamic and I know what I'm doing with them) Or if I feel like a real challenge, a 91-95 Caravan/Voyager with alllll the tricks in the motor and plug-in hybrid (Semi-through the road) that does 100mpg.