Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.

Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.

Automotive Calculators

New vs Used Car Comparison Calculator

2026-09-27 6 min

Net 5-year cost of new versus used after resale and catch-up maintenance.

New Net 5-Yr Cost: 17000 $
Used Net 5-Yr Cost: 11000 $
Difference (New-Used): 6000 $; positive = new costs more

Calculator

New Purchase Price($)

Used Purchase Price($)

New Resale (5-Yr)($)

Used Resale (5-Yr)($)

Used Catch-Up Maintenance($)

Results update live as you type

Live statistics

New Net 5-Yr Cost

17000 $

Used Net 5-Yr Cost

11000 $

Difference (New-Used)

6000 $

positive = new costs more

Results

Optimal

New Net 5-Yr Cost

17000$

Used Net 5-Yr Cost

11000$

Difference (New-Used)

6000$

positive = new costs more

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

17,000New Net 5-Yr Cost

11,000Used Net 5-Yr Cost

6,000Difference

Difference (New-Used) vs. New Purchase Price

Difference (New-Used)

6,000$

-10,00020,000

Formula

Depreciation-plus-maintenance view of the new-vs-used decision over five years.

New net = newPrice - newResale; used net = usedPrice + catchUp - usedResale; diff = newNet - usedNet

Alternative Form

Add insurance/fuel deltas for a full ownership total

Variables

Symbol	Name	Unit	Description
N	New net	$	Depreciation cost of buying new
U	Used net	$	Depreciation plus catch-up repairs

Explanation

Used cars dodge the steepest depreciation but owe catch-up maintenance — net cost balances the two.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

New Purchase Price:35000 $

Used Purchase Price:22000 $

New Resale (5-Yr):18000 $

Used Resale (5-Yr):14000 $

Used Catch-Up Maintenance:3000 $

Result: 5 inputs ready

Step 2

Apply the formula.

New net = newPrice - newResale; used net = usedPrice + catchUp - usedResale; diff = newNet - usedNet

Result: Primary result = 6000 $

Step 3

Read every derived output.

New Net 5-Yr Cost:17000 $

Used Net 5-Yr Cost:11000 $

Difference (New-Used):6000 $

Result: Difference (New-Used) = 6000 $

Final Answer

17000

Worked Examples

See how the calculator works with different scenarios.

Scenario

Same model, 3 years old.

Inputs

New:$35k, $18k resale

Used:$22k + $3k maint, $14k resale

Calculation

New net $17,000; used net $11,000; diff $6,000

Result

New costs $6,000 more net.

Interpretation

Used wins unless warranty and latest tech justify $6k.

Understanding Your Result

Your Result: New Net 5-Yr Cost: 17000 $

What This Means

Depreciation-led net cost gap over five years.

Why It Matters

New eats early depreciation; used eats repairs — net cost picks the real winner.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

•Double-check units on every input before trusting the result
•Compare against the worked example below to sanity-check magnitude
•Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

New vs used is steep early depreciation against catch-up repairs.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

Fill to first click at the same pump, record the odometer (Tank 0).
Drive normally for 2–3 tanks; always refill to first click at the same pump.
MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

•Get realistic resale quotes, not guesses
•Budget tires, brakes and fluids on used
•Certified used narrows the warranty gap

Common Mistakes

Mixing units (inches with mm, psi with kPa)

Convert every input to the unit shown on its field before calculating.

Trusting a single output blindly

Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.

Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.

No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

What is catch-up maintenance?

Deferred wear on a used car — tires, brakes, fluids, belts — that you pay soon after purchase.

Does financing change the answer?

Yes for cash flow, but net depreciation comparison still anchors the decision — add interest to each side.

Related Calculators

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Related Guides

Deepen your understanding with these educational resources.

Automotive Guides

Build planning, measurement protocol and validation how-tos

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG: Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km: Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe: Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE: Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance: Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag: Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling: Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II: On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

EPA — FuelEconomy.gov DOE — Fuel-Efficient Driving Tips NHTSA — Driving Safety & Efficiency SAE International — Fuel Economy Standards Consumer Reports — MPG Truth IRS — Standard Mileage Rates

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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Page Information

Last Updated:

2026-09-27

Version:

2.0.0

References:

License:

Free to use for educational and professional purposes.