Auto loan ''0% or $3000 off'' gimmick - Zero_Pct.WK1
''Zero-percent'' financing isn't zero interest, it's prepaid interest
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Determining monthly payments under the ''zero-percent'' scheme
With a nominal interest rate of zero (0%), (nominal means in name only), the payment equals the amount financed divided by the term. This simplifies calculating the monthly payment. But ''zero- percent'' financing isn't zero interest, it's prepaid interest. Prepaid interest leads to an unexpected and perverse effect, the larger the downpayment, the higher the true rate of interest.A downpayment (cash or trade-in) raises the cost of ''zero-percent'' financing
The cost of financing is higher with a large, or larger downpayment, or more valuable trade-in. The prepaid interest, included in the higher price paid to receive the financing, is spread over a smaller loan. Perversely, the more cash down, the smaller the loan, and the higher the true interest rate.Paying off the loan early (shortening the term)
Since the amount of interest is fixed in the higher initial price, an early payoff raises the rate. Lengthening the term would lower the rate. This is why the length of the term of so-called ''zero-percent'' financing is limited.
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Calculating the interest rate on alternative financing
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Determine the true rate on dealer financing, then shop for alternative financing.
A discounted cash flow analysis of dealer financing can deliver an APR (a nominal rate) and a true rate (APY). But alternative loans are quoted in APR. To compare loan rates from alternative sources, do a discounted cash flow analysis of the alternative loan's flows to find the true rate (APY). Then compare true rates.
If this seems complicated, try to remember that the banks wrote the rules to prevent easy comparisons.
Spreadsheet
The larger the downpayment, the higher the interest rate.
In this example, ''Zero down, zero-percent financing'' is really 15.26% (APR), true rate 16.38% (APY).
$2500 down increases the rate to 17.60% (APR), 19.09% (APY).
Calculate the interest rate by discounted cash flow [DCF]
Given:The vehicle can be purchased for cash, for $18,000
The vehicle can be financed, at $21,000 (higher price)
The term offered is 2 years (24 months)
The downpayment is zero ("nothing down")
The financing is nominally* zero percent (0%)
* Nominally means in name only.
DCF: the first value in a DCF calc is always negative.
Spreadsheet: If you're extending the number of payments, included all payments in @IRR's range.
| No Down | No Down | $2500 Down | $2500 Down | |
|---|---|---|---|---|
| APR | APY | APR | APY | |
| Calc> | 15.26 | 16.38 | 17.60 | 19.09 |
| Months | ||||
| 0 | -18000.00 | Cash value | -15500.00 | Cash value - down |
| 1 | 875.00 | FinValu/mos | 770.83 | FinValu/mos |
| 2 | 875.00 | 770.83 | ||
| 3 | 875.00 | 770.83 | ||
| 4 | 875.00 | 770.83 | ||
| 5 | 875.00 | 770.83 | ||
| 6 | 875.00 | 770.83 | ||
| 7 | 875.00 | 770.83 | ||
| 8 | 875.00 | 770.83 | ||
| 9 | 875.00 | 770.83 | ||
| 10 | 875.00 | 770.83 | ||
| 11 | 875.00 | 770.83 | ||
| 12 | 875.00 | 770.83 | ||
| 13 | 875.00 | 770.83 | ||
| 14 | 875.00 | 770.83 | ||
| 15 | 875.00 | 770.83 | ||
| 16 | 875.00 | 770.83 | ||
| 17 | 875.00 | 770.83 | ||
| 18 | 875.00 | 770.83 | ||
| 19 | 875.00 | 770.83 | ||
| 20 | 875.00 | 770.83 | ||
| 21 | 875.00 | 770.83 | ||
| 22 | 875.00 | 770.83 | ||
| 23 | 875.00 | 770.83 | ||
| 24 | 875.00 | 770.83 |