H.R.6620: To amend the Truth in Lending Act to limit the amount of the interchange fee imposed on the sale of motor vehicle fuel, and for other purposes.

Gas Pump Fair Payment Act of 2008 - Amends the Truth in Lending Act to prohibit an electronic payment system network, for a specified six-month period, from requiring or permitting a merchant to pay an interchange, processing, or other fee in connection with any credit, charge, or debit card transaction involving a consumer purchase of motor vehicle fuel in excess of 1% of the cost of each gallon of such fuel.