How much car can you actually afford?

Cars are the second-largest household expense after housing, and the one most often financed on vibes. Dealerships quote monthly payments, not total cost. The payment is a fraction of the true cost of owning the car — and calibrating on payment alone is exactly how households end up spending 20–25% of take-home on transportation and wondering why nothing else in the budget works.

The four costs of owning a car

• Depreciation — the resale value it loses each year. This is the biggest cost and the one people forget. A new car loses 20–30% in year one and roughly 15%/yr for the next few.
• Financing — the interest on the loan. On a $40k car at 8% over 6 years, that's about $10,300 in interest alone.
• Insurance — anywhere from $1,200 to $4,000+ per year depending on driver, region, and vehicle.
• Fuel and maintenance — assume $2,000–$4,000/yr for gas + routine maintenance, more for EVs on electricity but less on maintenance.

Add those up per month. On most new-car purchases, the true monthly cost is 1.7×–2× the loan payment. That's the number your budget actually has to absorb.

The 10/20/4 rule of thumb

• Total monthly car expenses (all four costs) ≤ 10% of take-home
• Down payment ≥ 20% (protects you from being underwater on the loan)
• Loan term ≤ 4 years

If a car can't be financed inside 4 years at a 20% down payment while staying under 10% of take-home, it's a car you can't afford — no matter what the dealer's payment calculator says.

Used vs. new — the cheat code most people ignore

The single most powerful lever on car cost isn't negotiation. It's letting someone else pay for year-one depreciation. A 3-year-old car with 40k km on it has already lost 40–50% of its value, comes with meaningful warranty life left on many models, and costs a fraction to insure and finance. If you're stretching to hit the 10% number on a new car, look at 2–4 years old first.

A worked example: what a $45,000 SUV actually costs per month

Purchase price $45,000, 20% down ($9,000), $36,000 financed at 7.5% over 5 years → $721/mo payment. Depreciation year one: ~$9,000, then ~$5,000/year for years 2–3, averaging ~$550/mo. Insurance in most Canadian provinces or US states for a mid-size SUV: $150–$250/mo. Fuel at 12,000 mi/yr and 25 mpg with gas at $4/gal: ~$160/mo. Maintenance reserve: $80/mo. Registration/tags: ~$15/mo. All-in: about $1,676/mo. For someone taking home $5,500/mo, that's 30% — three times the recommended ceiling — despite the 'affordable' $721 payment they were quoted.

Lease vs. buy vs. finance

• Lease — lowest payment, but you're paying for the steepest years of depreciation and owning nothing. Fits people who genuinely need a new car every 3 years and drive under the lease's km/mi cap.
• Finance — you own the car eventually. Cost is highest in years 1–2 (depreciation + interest both peak) and lowest in years 5+ once the loan is done.
• Cash — cheapest by far over the ownership period. But you lose the opportunity cost on the cash and, on a big purchase, may deplete the emergency fund.

The 'total transportation cost' reframe

The right ceiling isn't 'car budget' — it's total transportation. That includes ride-share, transit passes, parking, and a spouse's car. In a two-car household, 10% for both cars combined is more realistic than 10% each. In a city where transit works, downsizing to one car (or none) can free up 8–12% of take-home overnight — a bigger raise than most jobs ever give you.

Frequently asked questions

What about certified pre-owned? A reasonable middle ground — you pay a modest premium over private-party used for a warranty extension. Whether that's worth it depends on the model's known reliability.

Is 0% financing ever a deal? Sometimes, but not always — it's often offered on models where the manufacturer would otherwise give cash rebates. Compare 'cash back + finance elsewhere' vs '0% and no rebate' on total cost.

The takeaway

The right car budget starts from what your monthly numbers can absorb — not from a dealer's payment calculator working backwards from a $60k SUV. Ten percent of take-home, all-in, is the honest ceiling. Under 7% and you have real breathing room.