The bad the thing about the GM 6.2L is that premium fuel is recommended at all times unless you want less performance and fuel economy.
2017 Silverado Owners Manual
"For the 6.2L engine, premium
unleaded gasoline meeting ASTM
specification D4814 with a posted
octane rating of 93 is highly
recommended for best performance
and fuel economy. Unleaded
gasoline with an octane rated as low
as 87 can be used. Using unleaded
gasoline rated below 93 octane,
however, will lead to reduced
acceleration and fuel economy.
If knocking occurs, use a gasoline
rated at 93 octane as soon as
possible, otherwise, the engine
could be damaged. If heavy
knocking is heard when using
gasoline with a 93 octane rating, the
engine needs service."
3.5L Ecoboost(10-speed) towing 100 miles getting 9.1 mpg using AAA US average regular cost of $2.29= $25.16
6.2L Ecotec towing 100 miles getting 10.6 mpg using AAA US average premium cost of $2.82= $26.60
Oh, and in regards to Ecodiesel "haters"... I am still not a fan of it in a half ton regardless of the fuel mileage it gets. As I have said many times. The Ecodiesel is great for fuel mileage, but sucks in the power department compared to the other towing engines which is what I would rather have if the fuel mileage is withing my comfort zone. Just as I would pick a V8 Challenger of a V6 Challenger knowing that the V8 will get worse fuel economy.
