A big "if".
Here the least difference I see is $.60 per gallon, $.90 is more common and I've seen as much as $1.10 PER GALLON difference between grades. If we were still $.30 like you have, I wouldn't worry about it near as much.
If premium means "ethanol free" it does make more sense. But there is absolutely no such fuel here as "ethanol free". Nowhere.
And no, gas mileage isn't the ultimate be all end all or else I'd be driving a little **** box that would fit in the bed of my current truck...
I've never owned a FWD anything, and don't plan to.
I've only ever owned 1, 4 banger and it was in a Wrangler. And it was no better in that department than the other wrangler I had at the same time which had the inline 6. Just like my 318 Dakota's have tended to be better on fuel than my 3.9 powered ones.
I will never "not" have a truck of some sort.
I do like the best mileage I can get "for what they are" but how I drive and where I drive doesn't bode well for that to happen, so I do what I can.
I have 2 Durango s.... Which weren't known for being very good there either .. but having $0 monthly payments is nice.