type overpressure, aircon, glide with neutral gear, etc all sounded like make sense......but only on theory.
in real life they have no significant effect.

overpressure - safe 1 % of of FC but 4 tyres wear faster, maybe reduce 10-15% of tyre life.

off aircon - if u can tahan the heat, be my guess....

glide with neutral gear - u risking your life with no throttle (accelerate) to respond if u meet an accident, eg. need to speed up to avoid an incoming crash. not to mention clutch & gb wear faster with more frequent shifting. a cheapo gb cost u 5k, a cvt ot dsg could easily burn ur wallet with a price tag of 20k or more.

wanna be smart to save a few cent (ok maybe a ringgit or two) of each tank with the cost of tyre wear, gb wear, free sauna, trying to kill yourself by giving up the throttle? think again...

if u r driving a 2.0L or smaller, dont worry about FC.
if u r driving greater than 2.0L but wanna save some fuel? obviously u made a wrong choice, u bought the wrong car.