[MetroMPG]

Yup, correct.

You can also use the gauge to fine-tune your driving, then sell it later. But it's really worth the money - first time you have to read / reset a check-engine light, you'll be glad you have it.

Also: what mods have you done / do you have planned? With the majority of your driving being highway, there are a number of cheap (or free) and easy aero mods you can do, eg. a partial grille block.

Welcome to the forum!