VY Holden Commodore 3.8 Ecotec

[Wraven]

This thread is for my girlfriend’s Holden VY commodore sedan with a 3.8L ecotec

Context:
I daily drive this car and am working on making it better on fuel. This car sees lots of highway driving so making it as efficient as possible when cruising is my main goal, but still outwardly normal and presentable. I would also like to show people what the 3.8 ecotec is capable of

A bit of history:
When we bought the car it averaged 12.3L/100, as previous driver was a lead foot, and driving it normally have brought it down to around 10L/100. I had tried hypermiling in it but only got it down to around 8L/100, so put some thought to it and tried a few different things

Mods/work done to the common*****:
White Bosch injectors
Rislone race coolant
Low temp thermostat
Engine cleanup

Current successes are with the larger injectors, dropping the economy to 5.4L/100 on the freeway, which for a 3.8 ecotec, a single cam pushrod large displacement v6, based on an 80s design, is phenomenal.
I believe this works by confusing the ECU, meaning that it reduces power and fuel economy as well. Power has definitely been reduced as a result of these injectors, and a notable flat spot in the power curve around 3.5k rpm, but this car rarely reaches that and if it does it’s all laughs regardless as the car pulls like ****, which is fine


Future plans:
Sometime in the future I plan on turbocharging this car so all mods being done to it should hopefully work towards this goal. I am also trying to make this car quite presentable and otherwise very outwardly standard, so all ecomodding should be as inconspicuous as possible, such as an undertray, diffuser, and grill block off. I would also like to bag the car as this preserves daily driving and means I can slam the car when on the freeway and get my fuel usage down. I have a few other small aero tweaks that I will get on with in time which should all help but otherwise it should be a fairly presentable car