On a recent road trip I went from 19.3 mpg to 20.1 on my 2.7 4 door BD with wildtrak wheels/tires.
No eco goat mode. Just the regular driving blue themed one. Only thing I've done is change to the S&B Dry Intake filter. I use Shell 93 V-Power Nitro+.
I want to add that I used cruise control...
I was going to go Liqui Moly prior to my purchase, but after some research decided to go with Pennzoil Ultra Platinum. Seems to run really well so far.
I don't fill up much and 93 octane isn't terribly expensive here, I can find it under $4 a gallon usually so I fill up with Shell 93 V-Power Nitro+.
From the little I know about gas, anything labeled Top Tier is great fuel to use.