Now that my engine is broken in with over 1,700 miles, an oil change, and a tonneau cover, I try a highway MPG test again to see if those factors make a difference in MPG on the new 6.6L L8T gas engine with 10-speed Allison transmission. If you didn't catch my original MPG run, check out this video here:
   • MPG Test // I Drive 400+ Miles with M...  

00:00 Intro
03:15 Why is MPG All Over the Place?
07:43 Updates
12:51 MPG Results

Support the channel by browsing our online store, featuring most of the products featured and shown in today's video:
https://adventure.rocks/store/

#gmc #gmcsierra #truck @gmc