Wis. Admin. Code DFI-Bkg § 76.07
Upon consolidation of the unpaid balance of a retail installment contract for the purchase of a motor vehicle with the unpaid balance of any other transaction for the purchase of a motor vehicle, the customer shall receive a rebate of the unearned finance charge on each retail installment contract pursuant to the provisions of s. DFI- Bkg 76.04, except that for the purposes of computing that amount no minimum finance charge shall be allowed in consumer credit transactions. The rate of finance charge upon consolidation shall not exceed the maximum rate under s. 218.0142, Stats., applicable to the vehicle most recently purchased if the creditor is a licensed motor vehicle dealer. Otherwise the maximum rate shall not exceed the rate at which the creditor could loan the consolidated balance to the customer.
Wis. Admin. Code Department of Financial Institutions § DFI-Bkg 76.07