[MetroMPG]

Yes.

1) You could get ~60 mpg all day long cruising (on relatively level roads) in top gear at low RPM (ie. also low road speed - say ~40ish mph).

2) Or as others have said, you can get 60 mpg in sub/urban driving if you operate the car the way a hybrid works (ie. the engine is running only during acceleration, otherwise it's off).

Don't mess around with engine off techniques (a) unless you're an above average driver (aren't we all?) or (b) without practicing enough away from traffic to become proficient/second nature.

But why don't you want to do mods? There are effective ones that can be done that are free or cheap.