Documenting mileage is just that, documentation. Guys say they can tell mileage by brake pedal pad wear and set suppelness. It is still called documentation for a reason.
Years ago (ok, three years ago) I bought a 73 Satellite Sebring Plus off the side of the road. They guy was an anal retentive kinda guy. Notebooks for absoloutely every time the guy put gas in it, changed the oil, and all repairs. He noted mleage based on the predominate driving style of that fill up be it city or highway as well as where he bought the gas and price. The notes fell off in 2000 which pretty much matched the sticker on the tag and the car showed right at 79k.
Even though the car was a 318 with a slapstick with hubcaps, it sold for me on eBay for just over $14k. But it was rust free and evidently someone needed the car as the winner bid on the car and won from my computer. He actually said it it was not for that manilla folder of paper he would not have bid more than $8k.