Incremental Return on Credit Score?

[WNB]

IS anyone aware of any research out there on the incremental return one earns on improving your credit score?

From what I've read in basic 'consumer finance' literature is that if your credit score is in the average range, you have pretty much no trouble getting credit at average rates. I'm wondering, then, why we worry so much about getting the highest credit score possible. Is the improvement in the cost of credit really worth all that effort and money? (I've seen people here suggest that they would pay off debts they know are not legitimate simply to boost their score.)

I'm really curious what the actual "rate of return" on each credit score point above the national average is. I'm skeptical that credit costs really drop that much for people with the max score. (I'm quite sure, bankers being the greedy bastages they are, the rate of return on each point below the national average is probably very good. So if you have a weak credit score, it makes sense to try to improve it, but if you're average, I doubt further improvement makes much difference.)

[ShaggyDaddy]

I will give you a real life example. My father has top tier credit. I have medium low credit.

He bought a $25,000 car and paid $2440 in interest through the entire loan.
I bought a $15,000 car and paid $4505 in interest through the entire loan.

I have derogatories on my credit that total less than $2000. If I could/would have paid those off a year before getting the car, I would have saved a significant chunk of money regardless of if the debts are "real" or not, I would have saved money.