The man wants MORE caster. How about this idea?

I'm curious if some of you folks that change over to big caster -
If you kept track of fuel mileage before the change, then track it after, - cuz everytime you move the steering wheel, caster lifts one side of the car, - that's gonna use more power, even down a straight road, little tweek here/there, puts much bigger drag than it did before, in every turn.
You've heard how the engine slows when you turn the wheel when idling in the driveway.
Also interested if any tried going to 3* then 4* then 5* degrees caster, and when it stopped improving ?
Thnx
Great discussion.