Here's the page with the program facts:
https://hyundaimpginfo.com/resources/details/hyundai-reimbursement-program-facts
Looks like you register online, then you get your milage recorded by a Hyundai dealer.
Claim Process
Current owners (original and subsequent): To make a claim, current owners must: (1) register their contact information (by mail, email, fax or online via
www.HyundaiMPGinfo.com); and (2) obtain a mileage reading from an authorized Hyundai dealer.
Former owners (original and subsequent): To make a claim, former owners must: (1) register their contact information (by mail, email or fax); and (2) provide proof of mileage during their ownership of the vehicle (e.g., purchase and sale documents, odometer disclosure statements, smog certification, repair orders or other documents demonstrating mileage).
Owners who provide an email address will receive confirmation that Hyundai has received and is reviewing their claim. Once their claim has been approved, owners will be sent a debit card with their reimbursement.
Compensation
Mileage formula: Owners will be reimbursed based on: (1) 2012 average fuel prices for their geographic area times 1.15; (2) mileage accrued by the owner; (3) change in combined (city/hwy) EPA estimates for their vehicle; and (4) fuel grade (regular or premium) recommended for their vehicle.
2012 average fuel prices will be based on U.S. Energy Information Administration data for the owner’s geographic area (e.g., New England or Gulf Coast).
Choices: Owners will receive a debit card with reimbursement based on the above formula.
Applicable Time Period Limitations
Current and former owners may make a claim for mileage reimbursement beginning November 2, 2012. Owners must make their first claim within one year of November 2, 2012.
Current owners are advised to make one claim every calendar year, though they will be permitted to make more than one per year. They may also submit a second claim in a calendar year upon the sale of their subject vehicle. Former owners may make one claim (per vehicle).
Mileage will not be reimbursed for new owners taking ownership of any of the affected vehicles after November 2, 2012, excepting inter-family changes of ownership between immediate family members.
HMA Processing
Hyundai will review owner requests and send reimbursement within 120 days of their complete claim submission.