Sure, each item may not be measurable in the context of a whole tank. There's a lot of noise in daily driving that drowns it out. However, most of these items are measurable and verifiable as beneficial on their own in controlled testing. They ARE beneficial, and adding all of them together adds up to something useful. Drops in a bucket, maybe, but eventually you can fill a bucket with drops.
There's a reason the title is "The little things".
