[MetroMPG]

Hi Justin - welcome to the forum.

Congrats on learning to adjust the nut behind the wheel. 40% over EPA is nothing to sneeze at!

As for aero mods, my own experience has shown that the fuel economy gains from each individual mod I've investigated are about 2-3% at around 55 mph:

• 2.3% - kardboard kammback
• 2.3% - pass. mirror delete & driver's side fold back
• 5.7% - grille block & rear wheel skirts
• 2.2% - full undertray

Of these, you might as well do the easier ones first.

1. partial grille block (it'll also help with faster engine/transaxle warm-up)
2. passenger mirror delete, with inside convex replacement
3. underbody paneling

Some might suggest wheel skirts before underbody paneling, but I think rear skirts are likely less effective on larger cars than on small cars where the wheels are at the extreme rear of the vehicle.