[VBprogrammer]

It seems improbable that dealers / manufacturers can't do simple compound interest calculations too. If they are offering loans at below market rates they are basically giving you a discount on the cost. If they are willing to do that then you should be able to get a similar discount on a cash basis.

[hurricanetc]

Fed rates are low enough that banks can borrow and offer financing at seemingly impossibly low rates while still making money.