Well now, don't go making me out to be the VX God, lol. I've learned everything that I know about the VX through various readings that were given to me by several people on a couple of different boards. That, and spending some time with my own VX tearing apart and tinkering and putting things back together.
Let's just say that I'm good at getting VX info localized into one (or two, or even three) areas to share with others. Thus increasing the VX knowledge for the good of Ecomodder humanity!
Ok, I'm going to stop now, lol.
PS - It's kind of embarrassing to have such a bad average MPG on my VX as well. but I have a few things going against my car though; Bad thermostat (just replaced it the last week in Jan.), the weather was really cold for a month (Avg -10°F), a clutch that is on it's way out, and more than 370K miles on my motor now (the valve stem seals leak a tad of oil and the rings are going)....This spring the rebuilt D15Z1 goes in...along with the new drive shafts, new clutch, and new lower balljoints.
PPS - I've found that the NGK V-Power plugs work out the best in the D15Z1 (VX motor) NGK V-Power Spark Plugs No. ZFR4F-11
You've probably already read that in other posts but I'm just covering bases.