Hello! New here and need some help. I have had my used 2019 LTZ for about six months now. 5.3L 8sp. 80 some thousand miles on it. Mileage was about 16-17mpg initially. Now I'm lucky to get 12mpg. Everything is bone stock. I have bought the cheapest fuel I could get. I think I need to go to the 93 octane or stay away from the ethanol blend all together. Could it be that easy? Thanx in advance!!!

 

high octane fuel won't help. Ethanol free will help a little bit. Top factors are engine maintenance and driving habits.

 

Nothing has changed though. Except fuel. Thanx!

 

nothing that you're aware of. Try running some diagnostics.
Also, how are you calculating your economy?

 

I have only had it for about 6 months. Dealer did all services such as AF oil change etc. I check my mileage the old school way.
What diagnostics would you suggest? No codes stored is all I know at this point. Maybe better look at the air cleaner instead of trusting the dash. Thanx!