Of the subprime vehicle loans bundled into securities, 73 percent now exceed five years, up from 64 percent during the first three months of 2014, according to data from Citigroup Inc. Loans as long as seven years are increasingly being put into more bonds as auto-finance companies and Wall Street banks sell the securities at the fastest pace since 2007. The longer loans make it easier for consumers to afford rising new and used car prices by spreading out and lowering payments.