Took Marcos (Aspiras) Highway both up/down.
I don't know about "lots of sound insulation" but have ride with our company van using innova diesel and my gas innova and truly big difference.
I also put in my innova the hood insulation (to have less heat in the hood and also reduced noise, i think this is only installed in diesel).
Here's my current gas consumption (this is actual and not anyway via MID reading), i'm monitoring using apple apps (nice apps) every time i gas up i put up the odometer reading, the liters and the price as well.
So far average of 9.4 km/L (just about less than 2k km ODO):
