Hi Mark,
Welcome to the forum. I think you'll get your fuel economy up over time with some of the tips you find here. As for your Jetta, like ALL of our vehicles, adjusting the "nut behind the wheel" can have immediate positive {or negative in some cases} results. Hang in there. As for the previous mods on your car,
- 2" drop: probably helps since it reduces frontal area a bit (unless the lowered height makes it a snow plow in the winter
)
- air box mod: if it is to bring in cold air for higher performance, it will hurt your economy more often than not. Not exactly intuitive for some of us who learned mods as related to going faster.
- chip: I'm not familiar with a chip for improved fuel economy, so I can't make a contribution here.
- meaty snow tires: probably hinder economy, but if they keep the car moving and not buried in a snowbank this winter.............
Again, welcome
Another Mark