No question the biggest gains usually come from driving technique... and anyone making big gains from technique alone deserves kudos.
But why leave the low-hanging fruit on the tree?
Unless you're just trying to establish a "personal best" from technique alone. You know, man against machine etc. (nothing wrong with that).
But in my opinion,
not doing some of the easy, effective mods to your car is like choosing to ignore a poorly sealed door or window in your house. You could (A) turn up the heat, like the average Joe (waste energy!), (B) leave the heat down and do jumping jacks to stay warm inside when it's cold out (technique!), or (C) you could add/upgrade the weatherstripping (mod!).
OR... (D)you could upgrade the weatherstripping
and continue to do jumping jacks so you could turn down the heat even further and save even
more energy.
Just sayin'.