Decode a car lease offer — the money factor converted to APR, the cap-cost math, mileage and disposition traps, and what to negotiate. Use when asked to decode my car lease, is this lease deal good, what's a money factor, or review this lease before I sign. Produces the real-numbers decode (money factor → APR, total lease cost), the trap list with dollar exposure, and the negotiation points dealers expect to concede.
SKILL.md
Car Lease Decoder Skill
Leases are quoted in a dialect designed to prevent comparison: money factors instead of interest rates, cap costs instead of prices, payments instead of totals. This skill translates everything into the two numbers that matter — the effective APR and the total cost of the lease — then walks the traps that live in the back pages.
What This Skill Produces
The translation — money factor × 2400 = the APR they didn't say; cap cost vs MSRP vs negotiated price
Total lease cost — payments + drive-off + fees + likely end charges, one number
The trap list — mileage math, disposition fee, wear-and-tear standards, early-exit exposure, each priced
Negotiation points — what's routinely movable, with the asks
Required Inputs
Ask for these only if not provided:
The offer sheet — payment, term, miles/year, drive-off; ideally: money factor, residual %, cap cost, fees
The car — model and MSRP (residuals and negotiability vary)
Your driving reality — honest annual miles; the mileage trap is priced per your number
The alternative — buying the same car, if they want the comparison (chain to car-tco)
Framework
Money factor first: MF × 2400 = APR. Quote it back to the dealer as a rate. A "0.00325 money factor" is 7.8% — a number the customer can compare to their credit union. Also ask what MF the captive lender published — marked-up MF is dealer profit and negotiable.
depreciation (cap cost − residual) + rent charge ((cap + residual) × MF) + taxes/fees. Every offer decodes into this; anything that doesn't reconcile is a question.
The lease equation, shown:
Cap cost is the price — negotiate it exactly like a purchase price before ever discussing payment. "What payment do you want?" is the trap question; the decode answers with cap cost.
The mileage math, personalized: (your real miles − allowance) × per-mile charge × term. At 15k real vs 10k leased and $0.25/mile, that's $3,750 hiding behind a cheaper payment.
The end-of-lease gauntlet: disposition fee, wear standards ("excessive" defined by whom?), and the early-exit table — decode each with its dollar exposure and the one protective ask (e.g., waived disposition if leasing again).
Output Format
Lease Decode: [car] — [term]/[miles]
The two numbers: effective APR [n.n]% · total lease cost $[n] ([payments] + [drive-off] + [fees] + [projected end charges])
The equation, reconciled [depreciation + rent charge + fees vs their payment math — matches / gap of $n asks why]
Trap table | Trap | The line | Your exposure | The ask |
Negotiation points — cap cost, MF markup, mileage tier, disposition — each with wording
Lease vs buy pointer: [one honest paragraph; full math via car-tco]
End verbatim: "This is a plain-language reading, not financial advice — lease structures and taxes vary by jurisdiction; confirm anything load-bearing before signing."
Quality Checks
The money factor is converted to APR and the markup question is raised
Total lease cost is computed, not just the payment
Mileage exposure uses the user's real miles
Every trap carries a dollar exposure and a protective ask
The disclaimer appears verbatim
Anti-Patterns
Do not evaluate the payment — payments are the costume; APR and total cost are the deal
Do not accept the money factor as a mystical constant — it's a rate with a markup
Do not use the leased mileage in the math — use the driven mileage
Do not ignore the end-of-lease pages — that's where the cheap payment gets paid back
Do not declare lease vs buy universally — it depends on miles, years, and taxes; point to the calculator
