Guides

The arithmetic is one division. Every error is in the inputs — the dashboard readout, the supply-only rate, the averaged MPG, and the road-trip charger. Here is how each one moves the answer.

Federal law makes the dealer print the eleven numbers a lease payment is built from. Here is what each line means, which three decide the payment, and where the negotiating room actually is.

Payback is the price premium divided by the annual saving. Most published paybacks are too short because they count only fuel, and many still quietly subtract a federal credit that ended in 2025.

Falling short of the window sticker is normal, and the agency that prints the sticker says so. Here is what the combined figure actually is, the four things that thin it, and what the gap costs you in a year.

Most new-car buyers owe more than the car is worth on the day they sign, and the gap gets wider before it closes. Two situations make that a problem. Everything else is a number, not an emergency.

The rule compares the price of selling a car with the price of keeping it. Those answer different questions. What decides it is the repair bill divided by the miles it buys, against what the same miles cost in a replacement.

The average new-car loan now runs nearly seventy months, and a third are longer than six years. Stretching the term is the one lever that lowers the payment without lowering the price — here is what it costs in interest, and the larger thing it costs that nobody prints.

The Census measures your commute in minutes. Your bank account measures it in miles. Gasoline is about a sixth of the bill — and there are two defensible ways to price the rest, answering two different questions.

Most of what a car costs accrues on the calendar, not the odometer — so the same car in two driveways costs 124¢ a mile and 45¢ a mile. The per-mile figure is a fact about how much you drive, and fuel is rarely the line that decides it.

The formula is one multiplication, and it is not where trip budgets go wrong. They go wrong on four inputs — the drive home, a rating that does not survive the interstate, the charging price at the stall, and what splitting the gas leaves out.

Every affordability calculator inverts the loan formula and hands back the principal as though it were the price of a car. Two things are wrong with that, and both make the answer too big.

AAA's 2025 figures for nine vehicle categories, low to high — a 1.8x spread on identical assumptions. What the spread is actually made of, where the IRS rate lands inside it, and why the row for your category still isn't your car.

The EPA's combined MPG figure blends city and highway at a fixed 55/45 split that almost no driver matches exactly. Here's what that gap actually costs — and how to measure what your car really burns.

A trade-in credit looks like a discount but works like loan forgiveness — and when your car is underwater, a generous offer from the dealer can quietly add thousands in interest to your next loan.

Home charging cost is set by your utility rate, but public fast charging often tracks gasoline prices — and that divergence can move an EV's break-even mileage by thousands of miles depending on how you actually charge.