Fuel wasted in excessive rpm

[beneuan88]

My eg vti hatch (1.5l 130ps) runs at 3000rpm at 100km/h. At that speed i think it uses 5.3 odd litre per 100km. I think this costs me a lot of extra fuel, not so bad in rolling hilly country where neutral is used but on flat stretches T_T)

So if i use vtec e gearbox, 2300rpm at 100, potentially how much gas might i save? ive thought of something like 800ml per 100km, but i don't know what do you guys think?

my normal average for mix drive is 5l to 100km, id like to see low 4s.

[Daox]

It all differs from car to car.

Here are some examples though:

Regear for lower cruising RPM - EcoModder

Looks like they range from 7 to 20%. Pretty substantial.