Do I have to finance through the dealer?

No. You can pay cash, use a loan from your bank or credit union, or finance through the dealer. Getting pre-approved before you shop gives you a rate to compare, and a dealer may beat it. Some advertised discounts require dealer financing, so ask. On OffLot, the Build your deal step shows financing examples from sample lenders, and the preview pre-approval does not affect your credit; real credit checks are not live in the preview.