Your car loses money while it sits.

Roughly 18–20% for a mainstream model, and the drop starts the moment the title changes hands. The curve used here takes 18% in year one, then about 12% a year through year four, 7% a year to year ten and 4% a year after that. That front-loading is why a one-year-old car with 12,000 miles is so often the best value on the lot.

Age matters more early, mileage matters more later. A three-year-old car with 20,000 miles and one with 45,000 miles are priced close together; a ten-year-old car with 60,000 miles and one with 180,000 miles are not remotely comparable. This calculator applies the age curve first and then an extra reduction past roughly 31,000 and 62,000 miles.

Historically pickups, body-on-frame SUVs and a handful of reliability-reputation brands hold value well above the generic curve, while luxury sedans, large European saloons and early-generation EVs fall well below it. Supply matters too: anything with a long factory waiting list depreciates slowly until the backlog clears.

Because US auto insurance is rated on the driver, not the car. Age, ZIP code, claims history, annual mileage, marital status and — in most states — a credit-based insurance score move the premium far more than the vehicle value does. A percentage-of-value figure is only useful as a rough sanity check on quotes you already have.

The usual rule of thumb is when the annual premium for collision and comprehensive exceeds about 10% of the car’s actual cash value, because that is all the insurer will ever pay out, minus the deductible. On a car worth $3,000 with a $1,000 deductible, the most you can recover is $2,000 — check that against what the extra coverage costs you each year.

Almost never. Several states still set minimums in the 25/50/25 range — $25,000 per person for injury — and a single serious hospital stay clears that in days. Anything above the minimum is cheap relative to the exposure, and an umbrella policy on top is cheaper still.

The owner’s manual maintenance schedule is the definitive answer: if a timing belt replacement appears in it with a mileage, you have a belt. If the schedule says nothing about timing components, it is almost certainly a chain. Do not go by engine family alone — manufacturers have switched between the two within the same model line.

On an interference engine, the camshaft stops while the crankshaft keeps turning, and the valves collide with the pistons. Bent valves, damaged guides and sometimes cracked pistons follow, and the repair frequently exceeds the value of an older car. On a non-interference engine the car simply stops and you replace the belt, but those designs are increasingly rare.

On most belt-driven engines, yes. The pump sits behind the belt, so the labour is already being paid for, and a pump that fails 20,000 miles later means paying the entire job again. The same logic applies to the tensioner and idler pulleys.

Yes. Manufacturers commonly specify replacement at seven to ten years regardless of the odometer, because the rubber and its reinforcing cords degrade with heat cycling and age. A low-mileage car that spent a decade in a hot climate is exactly the case where people get caught out.

Run the projection case to get a residual value at the end of the lease term, then compare it with the residual the leasing company is assuming — it is implied by the monthly payment and the buyout price. If their residual is much higher than this estimate, the lease is being subsidised and may be the cheaper route; if it is much lower, you are paying for their caution.