{
  "$comment": "Machine-readable companion to https://valem.run/calculators/tools/car-tco. Formula, inputs, outputs, engine-verified test vectors, cited sources and the re-runnable Valem ModelSpec behind the page.",
  "url": "https://valem.run/calculators/tools/car-tco",
  "dataUrl": "https://valem.run/calculators/tools/car-tco.json",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Decision tools car total cost of ownership model by Valem (https://valem.run/calculators/tools/car-tco), CC BY 4.0.",
    "note": "Covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds themselves are law and are not licensed by anyone; the cited sources are where they come from."
  },
  "verificationUrl": "https://valem.run/calculators/tools/car-tco/verify",
  "country": "tools",
  "countryName": "Decision tools",
  "formula": "car-tco",
  "formulaName": "Car total cost of ownership",
  "title": "Car Total Cost of Ownership Calculator",
  "answer": "The true cost of owning a car is its depreciation plus finance interest, fuel or electricity, insurance, servicing, tyres, tax and the incidentals — and depreciation is usually the largest line, which is why both the sticker price and the monthly payment understate it.",
  "lang": "en",
  "currency": "USD",
  "taxYear": "",
  "verification": {
    "claim": "internal-consistency",
    "statement": "The Valem engine reproduces this model's stated formula through 3 self-test cases (below, and re-runnable against the spec). That asserts internal consistency, NOT that the formula matches current law — the cited sources are the evidence for that, and carry the date each was last checked.",
    "selfTestCases": 3,
    "ratesAreIllustrative": false,
    "sourcesCheckedOn": "2026-08-02"
  },
  "sources": [],
  "terminalOutput": "depreciationShare",
  "inputs": [
    {
      "name": "purchasePrice",
      "type": "number",
      "label": "Purchase price",
      "minimum": 0
    },
    {
      "name": "deposit",
      "type": "number",
      "label": "Deposit",
      "minimum": 0
    },
    {
      "name": "tradeIn",
      "type": "number",
      "label": "Trade-in value",
      "minimum": 0
    },
    {
      "name": "aprPct",
      "type": "number",
      "label": "Finance APR (%)",
      "minimum": 0,
      "maximum": 40
    },
    {
      "name": "loanTermMonths",
      "type": "integer",
      "label": "Finance term (months)",
      "minimum": 0,
      "maximum": 120
    },
    {
      "name": "years",
      "type": "integer",
      "label": "Years you keep it",
      "minimum": 1,
      "maximum": 15
    },
    {
      "name": "annualDistance",
      "type": "number",
      "label": "Distance per year (km)",
      "minimum": 0
    },
    {
      "name": "fuelType",
      "type": "string",
      "label": "Fuel type",
      "enum": [
        "petrol",
        "diesel",
        "hybrid",
        "ev"
      ]
    },
    {
      "name": "consumptionPer100",
      "type": "number",
      "label": "Consumption per 100 km (L, or kWh for an EV)",
      "minimum": 0
    },
    {
      "name": "unitPrice",
      "type": "number",
      "label": "Price per litre (or per kWh)",
      "minimum": 0
    },
    {
      "name": "insurancePerYear",
      "type": "number",
      "label": "Insurance per year",
      "minimum": 0
    },
    {
      "name": "servicingPerYear",
      "type": "number",
      "label": "Servicing per year",
      "minimum": 0
    },
    {
      "name": "repairsPerYear",
      "type": "number",
      "label": "Repairs allowance per year",
      "minimum": 0
    },
    {
      "name": "tyreSetCost",
      "type": "number",
      "label": "Cost of a set of tyres",
      "minimum": 0
    },
    {
      "name": "tyreLifeKm",
      "type": "number",
      "label": "Tyre life (km)",
      "minimum": 1
    },
    {
      "name": "roadTaxPerYear",
      "type": "number",
      "label": "Road tax per year",
      "minimum": 0
    },
    {
      "name": "inspectionPerYear",
      "type": "number",
      "label": "Inspection per year",
      "minimum": 0
    },
    {
      "name": "parkingPerYear",
      "type": "number",
      "label": "Parking per year",
      "minimum": 0
    },
    {
      "name": "tollsPerYear",
      "type": "number",
      "label": "Tolls per year",
      "minimum": 0
    },
    {
      "name": "breakdownCoverPerYear",
      "type": "number",
      "label": "Breakdown cover per year",
      "minimum": 0
    }
  ],
  "outputs": [
    {
      "name": "financedAmount",
      "type": "number",
      "formula": "$max([0, $round(purchasePrice - deposit - tradeIn, 2)])"
    },
    {
      "name": "monthlyRate",
      "type": "number",
      "formula": "aprPct / 1200"
    },
    {
      "name": "compoundFactor",
      "type": "number",
      "formula": "$power(1 + monthlyRate, loanTermMonths)"
    },
    {
      "name": "monthlyPayment",
      "type": "number",
      "label": "Monthly finance payment",
      "format": "number",
      "formula": "(financedAmount <= 0 or loanTermMonths <= 0) ? 0 : (monthlyRate = 0 ? $round(financedAmount / loanTermMonths, 2) : $round(financedAmount * monthlyRate * compoundFactor / (compoundFactor - 1), 2))"
    },
    {
      "name": "totalInterest",
      "type": "number",
      "label": "Finance interest",
      "format": "number",
      "formula": "$max([0, $round(monthlyPayment * loanTermMonths - financedAmount, 2)])"
    },
    {
      "name": "residualValue",
      "type": "number",
      "label": "Resale value at the end",
      "format": "number",
      "formula": "$round(purchasePrice * $residualPct(years, $const.residualCurve, $const.tailDepreciation), 2)"
    },
    {
      "name": "totalDepreciation",
      "type": "number",
      "label": "Depreciation",
      "format": "number",
      "formula": "$round(purchasePrice - residualValue, 2)"
    },
    {
      "name": "energyCostPerYear",
      "type": "number",
      "formula": "$round(annualDistance / 100 * consumptionPer100 * unitPrice, 2)"
    },
    {
      "name": "tyreCostPerYear",
      "type": "number",
      "formula": "$round($ceil(annualDistance * years / tyreLifeKm) * tyreSetCost / years, 2)"
    },
    {
      "name": "fixedCostPerYear",
      "type": "number",
      "formula": "$round(insurancePerYear + servicingPerYear + repairsPerYear + roadTaxPerYear + inspectionPerYear + parkingPerYear + tollsPerYear + breakdownCoverPerYear, 2)"
    },
    {
      "name": "yearly",
      "type": "array",
      "label": "What you pay each year, by cost category",
      "formula": "$map([1..years], function($y) { ( $m1 := $min([($y - 1) * 12, loanTermMonths]); $m2 := $min([$y * 12, loanTermMonths]); $b1 := $balanceAt($m1, financedAmount, monthlyRate, compoundFactor, loanTermMonths); $b2 := $balanceAt($m2, financedAmount, monthlyRate, compoundFactor, loanTermMonths); $int := $max([0, $round(monthlyPayment * ($m2 - $m1) - ($b1 - $b2), 2)]); $v0 := $round(purchasePrice * $residualPct($y - 1, $const.residualCurve, $const.tailDepreciation), 2); $v1 := $round(purchasePrice * $residualPct($y, $const.residualCurve, $const.tailDepreciation), 2); $dep := $round($v0 - $v1, 2); $cumInt := $max([0, $round(monthlyPayment * $m2 - (financedAmount - $b2), 2)]); {\"year\": $y, \"depreciation\": $dep, \"interest\": $int, \"energy\": energyCostPerYear, \"tyres\": tyreCostPerYear, \"fixed\": fixedCostPerYear, \"total\": $round($dep + $int + energyCostPerYear + tyreCostPerYear + fixedCostPerYear, 2), \"cumulative\": $round(purchasePrice - $v1 + $cumInt + $y * (energyCostPerYear + tyreCostPerYear + fixedCostPerYear), 2)} ) })"
    },
    {
      "name": "totalCost",
      "type": "number",
      "label": "Total cost of ownership",
      "format": "number",
      "formula": "$round($sum($map(yearly, function($r) { $r.total })), 2)"
    },
    {
      "name": "costPerKm",
      "type": "number",
      "label": "Cost per km",
      "format": "number",
      "formula": "annualDistance <= 0 ? 0 : $round(totalCost / (annualDistance * years), 4)"
    },
    {
      "name": "costPerMonth",
      "type": "number",
      "label": "Cost per month",
      "format": "number",
      "formula": "$round(totalCost / (years * 12), 2)"
    },
    {
      "name": "depreciationShare",
      "type": "number",
      "label": "Depreciation share",
      "format": "number",
      "formula": "totalCost <= 0 ? 0 : $round(totalDepreciation / totalCost * 100, 1)"
    }
  ],
  "testCases": [
    {
      "description": "32,000 petrol car on 6.5% finance over 60 months, 15,000 km a year, kept five years",
      "given": {
        "purchasePrice": 32000,
        "deposit": 6000,
        "aprPct": 6.5,
        "loanTermMonths": 60,
        "years": 5,
        "annualDistance": 15000
      },
      "expect": {
        "financedAmount": 26000,
        "monthlyPayment": 508.72,
        "totalInterest": 4523.2,
        "residualValue": 15680,
        "totalDepreciation": 16320,
        "energyCostPerYear": 1706.25,
        "tyreCostPerYear": 192,
        "fixedCostPerYear": 1960,
        "yearly[0].depreciation": 6400,
        "yearly[0].interest": 1556.08,
        "yearly[0].total": 11814.33,
        "yearly[4].cumulative": 40134.45,
        "totalCost": 40134.45,
        "costPerKm": 0.5351,
        "costPerMonth": 668.91,
        "depreciationShare": 40.7
      }
    },
    {
      "description": "the same car bought for cash — the total falls by exactly the finance interest",
      "given": {
        "deposit": 32000
      },
      "expect": {
        "financedAmount": 0,
        "monthlyPayment": 0,
        "totalInterest": 0,
        "totalCost": 35611.25,
        "costPerKm": 0.4748,
        "costPerMonth": 593.52
      }
    },
    {
      "description": "the same car as an EV at 17 kWh/100 km and 0.28 per kWh — only the energy line changes",
      "given": {
        "fuelType": "ev",
        "consumptionPer100": 17,
        "unitPrice": 0.28
      },
      "expect": {
        "energyCostPerYear": 714,
        "totalInterest": 4523.2,
        "totalDepreciation": 16320,
        "totalCost": 35173.2,
        "costPerKm": 0.469,
        "depreciationShare": 46.4
      }
    }
  ],
  "spec": {
    "id": "car-tco",
    "version": "1.0.0",
    "schema": {
      "type": "object",
      "properties": {
        "purchasePrice": {
          "type": "number",
          "minimum": 0,
          "description": "List price paid for the car"
        },
        "deposit": {
          "type": "number",
          "minimum": 0,
          "description": "Cash paid up front"
        },
        "tradeIn": {
          "type": "number",
          "minimum": 0,
          "description": "Value of a car traded in"
        },
        "aprPct": {
          "type": "number",
          "minimum": 0,
          "maximum": 40,
          "description": "Finance APR, percent"
        },
        "loanTermMonths": {
          "type": "integer",
          "minimum": 0,
          "maximum": 120
        },
        "years": {
          "type": "integer",
          "minimum": 1,
          "maximum": 15,
          "description": "How long you keep the car"
        },
        "annualDistance": {
          "type": "number",
          "minimum": 0,
          "description": "Distance driven per year"
        },
        "fuelType": {
          "type": "string",
          "enum": [
            "petrol",
            "diesel",
            "hybrid",
            "ev"
          ]
        },
        "consumptionPer100": {
          "type": "number",
          "minimum": 0,
          "description": "Litres per 100 km, or kWh per 100 km for an EV"
        },
        "unitPrice": {
          "type": "number",
          "minimum": 0,
          "description": "Price per litre, or per kWh for an EV"
        },
        "insurancePerYear": {
          "type": "number",
          "minimum": 0
        },
        "servicingPerYear": {
          "type": "number",
          "minimum": 0
        },
        "repairsPerYear": {
          "type": "number",
          "minimum": 0,
          "description": "Allowance for unscheduled repairs"
        },
        "tyreSetCost": {
          "type": "number",
          "minimum": 0
        },
        "tyreLifeKm": {
          "type": "number",
          "minimum": 1
        },
        "roadTaxPerYear": {
          "type": "number",
          "minimum": 0
        },
        "inspectionPerYear": {
          "type": "number",
          "minimum": 0
        },
        "parkingPerYear": {
          "type": "number",
          "minimum": 0
        },
        "tollsPerYear": {
          "type": "number",
          "minimum": 0
        },
        "breakdownCoverPerYear": {
          "type": "number",
          "minimum": 0
        },
        "financedAmount": {
          "type": "number",
          "readOnly": true
        },
        "monthlyRate": {
          "type": "number",
          "readOnly": true
        },
        "compoundFactor": {
          "type": "number",
          "readOnly": true
        },
        "monthlyPayment": {
          "type": "number",
          "readOnly": true
        },
        "totalInterest": {
          "type": "number",
          "readOnly": true
        },
        "residualValue": {
          "type": "number",
          "readOnly": true
        },
        "totalDepreciation": {
          "type": "number",
          "readOnly": true
        },
        "energyCostPerYear": {
          "type": "number",
          "readOnly": true
        },
        "tyreCostPerYear": {
          "type": "number",
          "readOnly": true
        },
        "fixedCostPerYear": {
          "type": "number",
          "readOnly": true
        },
        "yearly": {
          "type": "array",
          "readOnly": true,
          "items": {
            "type": "object",
            "properties": {
              "year": {
                "type": "integer"
              },
              "depreciation": {
                "type": "number"
              },
              "interest": {
                "type": "number"
              },
              "energy": {
                "type": "number"
              },
              "tyres": {
                "type": "number"
              },
              "fixed": {
                "type": "number"
              },
              "total": {
                "type": "number"
              },
              "cumulative": {
                "type": "number"
              }
            }
          }
        },
        "totalCost": {
          "type": "number",
          "readOnly": true
        },
        "costPerKm": {
          "type": "number",
          "readOnly": true
        },
        "costPerMonth": {
          "type": "number",
          "readOnly": true
        },
        "depreciationShare": {
          "type": "number",
          "readOnly": true
        }
      },
      "required": [
        "purchasePrice",
        "years",
        "annualDistance"
      ]
    },
    "constants": {
      "residualCurve": [
        0.8,
        0.7,
        0.62,
        0.55,
        0.49,
        0.44,
        0.39,
        0.35,
        0.31,
        0.28
      ],
      "tailDepreciation": 0.1
    },
    "library": {
      "layers": [
        {
          "define": "( $residualPct := function($year, $curve, $tail) { $year <= 0 ? 1 : ($year <= 10 ? $curve[$year - 1] : $curve[9] * $power(1 - $tail, $year - 10)) }; $balanceAt := function($m, $principal, $rate, $factor, $term) { ($term <= 0 or $principal <= 0) ? 0 : ($rate = 0 ? $principal * (1 - $m / $term) : $principal * ($factor - $power(1 + $rate, $m)) / ($factor - 1)) }; [\"residualPct\", \"balanceAt\"] )"
        }
      ]
    },
    "defaultValues": [
      {
        "path": "$",
        "expr": "{\"purchasePrice\": 32000, \"deposit\": 6000, \"tradeIn\": 0, \"aprPct\": 6.5, \"loanTermMonths\": 60, \"years\": 5, \"annualDistance\": 15000, \"fuelType\": \"petrol\", \"consumptionPer100\": 6.5, \"unitPrice\": 1.75, \"insurancePerYear\": 650, \"servicingPerYear\": 400, \"repairsPerYear\": 250, \"tyreSetCost\": 480, \"tyreLifeKm\": 40000, \"roadTaxPerYear\": 180, \"inspectionPerYear\": 40, \"parkingPerYear\": 300, \"tollsPerYear\": 60, \"breakdownCoverPerYear\": 80}"
      }
    ],
    "derivations": [
      {
        "path": "$.financedAmount",
        "expr": "$max([0, $round(purchasePrice - deposit - tradeIn, 2)])"
      },
      {
        "path": "$.monthlyRate",
        "expr": "aprPct / 1200"
      },
      {
        "path": "$.energyCostPerYear",
        "expr": "$round(annualDistance / 100 * consumptionPer100 * unitPrice, 2)"
      },
      {
        "path": "$.tyreCostPerYear",
        "expr": "$round($ceil(annualDistance * years / tyreLifeKm) * tyreSetCost / years, 2)"
      },
      {
        "path": "$.fixedCostPerYear",
        "expr": "$round(insurancePerYear + servicingPerYear + repairsPerYear + roadTaxPerYear + inspectionPerYear + parkingPerYear + tollsPerYear + breakdownCoverPerYear, 2)"
      },
      {
        "path": "$.residualValue",
        "expr": "$round(purchasePrice * $residualPct(years, $const.residualCurve, $const.tailDepreciation), 2)"
      },
      {
        "path": "$.compoundFactor",
        "expr": "$power(1 + monthlyRate, loanTermMonths)"
      },
      {
        "path": "$.totalDepreciation",
        "expr": "$round(purchasePrice - residualValue, 2)"
      },
      {
        "path": "$.monthlyPayment",
        "expr": "(financedAmount <= 0 or loanTermMonths <= 0) ? 0 : (monthlyRate = 0 ? $round(financedAmount / loanTermMonths, 2) : $round(financedAmount * monthlyRate * compoundFactor / (compoundFactor - 1), 2))"
      },
      {
        "path": "$.totalInterest",
        "expr": "$max([0, $round(monthlyPayment * loanTermMonths - financedAmount, 2)])"
      },
      {
        "path": "$.yearly",
        "expr": "$map([1..years], function($y) { ( $m1 := $min([($y - 1) * 12, loanTermMonths]); $m2 := $min([$y * 12, loanTermMonths]); $b1 := $balanceAt($m1, financedAmount, monthlyRate, compoundFactor, loanTermMonths); $b2 := $balanceAt($m2, financedAmount, monthlyRate, compoundFactor, loanTermMonths); $int := $max([0, $round(monthlyPayment * ($m2 - $m1) - ($b1 - $b2), 2)]); $v0 := $round(purchasePrice * $residualPct($y - 1, $const.residualCurve, $const.tailDepreciation), 2); $v1 := $round(purchasePrice * $residualPct($y, $const.residualCurve, $const.tailDepreciation), 2); $dep := $round($v0 - $v1, 2); $cumInt := $max([0, $round(monthlyPayment * $m2 - (financedAmount - $b2), 2)]); {\"year\": $y, \"depreciation\": $dep, \"interest\": $int, \"energy\": energyCostPerYear, \"tyres\": tyreCostPerYear, \"fixed\": fixedCostPerYear, \"total\": $round($dep + $int + energyCostPerYear + tyreCostPerYear + fixedCostPerYear, 2), \"cumulative\": $round(purchasePrice - $v1 + $cumInt + $y * (energyCostPerYear + tyreCostPerYear + fixedCostPerYear), 2)} ) })"
      },
      {
        "path": "$.totalCost",
        "expr": "$round($sum($map(yearly, function($r) { $r.total })), 2)"
      },
      {
        "path": "$.costPerKm",
        "expr": "annualDistance <= 0 ? 0 : $round(totalCost / (annualDistance * years), 4)"
      },
      {
        "path": "$.costPerMonth",
        "expr": "$round(totalCost / (years * 12), 2)"
      },
      {
        "path": "$.depreciationShare",
        "expr": "totalCost <= 0 ? 0 : $round(totalDepreciation / totalCost * 100, 1)"
      }
    ],
    "constraints": [
      {
        "id": "price-positive",
        "expr": "purchasePrice > 0",
        "message": "Purchase price must be positive",
        "policy": "rollback"
      },
      {
        "id": "deposit-within-price",
        "expr": "deposit + tradeIn <= purchasePrice",
        "message": "Deposit plus trade-in cannot exceed the purchase price",
        "policy": "rollback"
      },
      {
        "id": "term-within-ownership",
        "expr": "loanTermMonths <= years * 12",
        "message": "The finance term runs longer than you plan to keep the car — the figures below only count interest paid while you own it",
        "policy": "flag"
      }
    ],
    "viewDefinition": {
      "renderer": "builtin",
      "defaultView": "main",
      "views": [
        {
          "id": "main",
          "label": "Car cost of ownership",
          "layout": "vertical",
          "components": [
            {
              "id": "assumptions",
              "type": "alert",
              "variant": "info",
              "label": "This is a projection from your assumptions",
              "text": "Every figure below follows from the numbers you enter. Depreciation uses a typical retained-value curve, not your car's actual resale price, and finance interest assumes the payment is never missed or overpaid. Change any input to see the whole breakdown re-price. Not financial advice."
            },
            {
              "id": "purchaseSet",
              "type": "fieldSet",
              "legend": "Buying and financing",
              "components": [
                {
                  "id": "purchasePriceField",
                  "type": "numericField",
                  "label": "Purchase price",
                  "bind": "$.purchasePrice",
                  "placeholder": "32000"
                },
                {
                  "id": "depositField",
                  "type": "numericField",
                  "label": "Deposit",
                  "bind": "$.deposit",
                  "placeholder": "6000"
                },
                {
                  "id": "tradeInField",
                  "type": "numericField",
                  "label": "Trade-in value",
                  "bind": "$.tradeIn",
                  "placeholder": "0"
                },
                {
                  "id": "aprField",
                  "type": "numericField",
                  "label": "Finance APR (%)",
                  "bind": "$.aprPct",
                  "placeholder": "6.5"
                },
                {
                  "id": "termField",
                  "type": "numericField",
                  "label": "Finance term (months)",
                  "bind": "$.loanTermMonths",
                  "placeholder": "60"
                },
                {
                  "id": "yearsField",
                  "type": "sliderField",
                  "label": "Years you keep it",
                  "bind": "$.years",
                  "min": 1,
                  "max": 15,
                  "step": 1
                }
              ]
            },
            {
              "id": "runningSet",
              "type": "fieldSet",
              "legend": "Driving and energy",
              "components": [
                {
                  "id": "distanceField",
                  "type": "numericField",
                  "label": "Distance per year (km)",
                  "bind": "$.annualDistance",
                  "placeholder": "15000"
                },
                {
                  "id": "fuelTypeField",
                  "type": "selectField",
                  "label": "Fuel type",
                  "bind": "$.fuelType",
                  "options": [
                    {
                      "value": "petrol",
                      "label": "Petrol"
                    },
                    {
                      "value": "diesel",
                      "label": "Diesel"
                    },
                    {
                      "value": "hybrid",
                      "label": "Hybrid"
                    },
                    {
                      "value": "ev",
                      "label": "Electric"
                    }
                  ]
                },
                {
                  "id": "consumptionField",
                  "type": "numericField",
                  "label": "Consumption per 100 km (L, or kWh for an EV)",
                  "bind": "$.consumptionPer100",
                  "placeholder": "6.5"
                },
                {
                  "id": "unitPriceField",
                  "type": "numericField",
                  "label": "Price per litre (or per kWh)",
                  "bind": "$.unitPrice",
                  "placeholder": "1.75"
                }
              ]
            },
            {
              "id": "upkeepSet",
              "type": "fieldSet",
              "legend": "Upkeep and standing costs",
              "components": [
                {
                  "id": "insuranceField",
                  "type": "numericField",
                  "label": "Insurance per year",
                  "bind": "$.insurancePerYear",
                  "placeholder": "650"
                },
                {
                  "id": "servicingField",
                  "type": "numericField",
                  "label": "Servicing per year",
                  "bind": "$.servicingPerYear",
                  "placeholder": "400"
                },
                {
                  "id": "repairsField",
                  "type": "numericField",
                  "label": "Repairs allowance per year",
                  "bind": "$.repairsPerYear",
                  "placeholder": "250"
                },
                {
                  "id": "tyreCostField",
                  "type": "numericField",
                  "label": "Cost of a set of tyres",
                  "bind": "$.tyreSetCost",
                  "placeholder": "480"
                },
                {
                  "id": "tyreLifeField",
                  "type": "numericField",
                  "label": "Tyre life (km)",
                  "bind": "$.tyreLifeKm",
                  "placeholder": "40000"
                },
                {
                  "id": "roadTaxField",
                  "type": "numericField",
                  "label": "Road tax per year",
                  "bind": "$.roadTaxPerYear",
                  "placeholder": "180"
                },
                {
                  "id": "inspectionField",
                  "type": "numericField",
                  "label": "Inspection per year",
                  "bind": "$.inspectionPerYear",
                  "placeholder": "40"
                },
                {
                  "id": "parkingField",
                  "type": "numericField",
                  "label": "Parking per year",
                  "bind": "$.parkingPerYear",
                  "placeholder": "300"
                },
                {
                  "id": "tollsField",
                  "type": "numericField",
                  "label": "Tolls per year",
                  "bind": "$.tollsPerYear",
                  "placeholder": "60"
                },
                {
                  "id": "breakdownField",
                  "type": "numericField",
                  "label": "Breakdown cover per year",
                  "bind": "$.breakdownCoverPerYear",
                  "placeholder": "80"
                }
              ]
            },
            {
              "id": "sep1",
              "type": "separatorLine"
            },
            {
              "id": "headline",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "totalTile",
                  "type": "statTile",
                  "label": "Total cost of ownership",
                  "bind": "$.totalCost",
                  "format": "number",
                  "caption": "over the whole period"
                },
                {
                  "id": "perMonthTile",
                  "type": "statTile",
                  "label": "Cost per month",
                  "bind": "$.costPerMonth",
                  "format": "number"
                },
                {
                  "id": "perKmTile",
                  "type": "statTile",
                  "label": "Cost per km",
                  "bind": "$.costPerKm",
                  "format": "number"
                },
                {
                  "id": "depShareTile",
                  "type": "statTile",
                  "label": "Depreciation share",
                  "bind": "$.depreciationShare",
                  "format": "number",
                  "caption": "% of the total"
                }
              ]
            },
            {
              "id": "secondary",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "depTile",
                  "type": "statTile",
                  "label": "Depreciation",
                  "bind": "$.totalDepreciation",
                  "format": "number"
                },
                {
                  "id": "interestTile",
                  "type": "statTile",
                  "label": "Finance interest",
                  "bind": "$.totalInterest",
                  "format": "number"
                },
                {
                  "id": "residualTile",
                  "type": "statTile",
                  "label": "Resale value at the end",
                  "bind": "$.residualValue",
                  "format": "number"
                },
                {
                  "id": "paymentTile",
                  "type": "statTile",
                  "label": "Monthly finance payment",
                  "bind": "$.monthlyPayment",
                  "format": "number"
                }
              ]
            },
            {
              "id": "sep2",
              "type": "separatorLine"
            },
            {
              "id": "breakdownChart",
              "type": "dataChart",
              "label": "What you pay each year, by cost category",
              "chartType": "bar",
              "bind": "$.yearly",
              "chartX": "year",
              "chartSeries": [
                {
                  "field": "depreciation",
                  "label": "Depreciation"
                },
                {
                  "field": "interest",
                  "label": "Finance interest"
                },
                {
                  "field": "energy",
                  "label": "Fuel / electricity"
                },
                {
                  "field": "tyres",
                  "label": "Tyres"
                },
                {
                  "field": "fixed",
                  "label": "Insurance, tax and upkeep"
                }
              ]
            },
            {
              "id": "breakdownTable",
              "type": "dataTable",
              "label": "Year by year",
              "bind": "$.yearly",
              "tableColumns": [
                {
                  "field": "year",
                  "header": "Year",
                  "width": "10%"
                },
                {
                  "field": "depreciation",
                  "header": "Depreciation",
                  "format": "number",
                  "width": "16%"
                },
                {
                  "field": "interest",
                  "header": "Interest",
                  "format": "number",
                  "width": "14%"
                },
                {
                  "field": "energy",
                  "header": "Energy",
                  "format": "number",
                  "width": "14%"
                },
                {
                  "field": "tyres",
                  "header": "Tyres",
                  "format": "number",
                  "width": "12%"
                },
                {
                  "field": "fixed",
                  "header": "Upkeep",
                  "format": "number",
                  "width": "14%"
                },
                {
                  "field": "total",
                  "header": "Year total",
                  "format": "number",
                  "width": "20%"
                }
              ],
              "pageSize": 15
            }
          ]
        }
      ]
    },
    "tests": [
      {
        "description": "32,000 petrol car on 6.5% finance over 60 months, 15,000 km a year, kept five years",
        "given": {
          "$.purchasePrice": 32000,
          "$.deposit": 6000,
          "$.aprPct": 6.5,
          "$.loanTermMonths": 60,
          "$.years": 5,
          "$.annualDistance": 15000
        },
        "expect": {
          "$.financedAmount": 26000,
          "$.monthlyPayment": 508.72,
          "$.totalInterest": 4523.2,
          "$.residualValue": 15680,
          "$.totalDepreciation": 16320,
          "$.energyCostPerYear": 1706.25,
          "$.tyreCostPerYear": 192,
          "$.fixedCostPerYear": 1960,
          "$.yearly[0].depreciation": 6400,
          "$.yearly[0].interest": 1556.08,
          "$.yearly[0].total": 11814.33,
          "$.yearly[4].cumulative": 40134.45,
          "$.totalCost": 40134.45,
          "$.costPerKm": 0.5351,
          "$.costPerMonth": 668.91,
          "$.depreciationShare": 40.7
        }
      },
      {
        "description": "the same car bought for cash — the total falls by exactly the finance interest",
        "given": {
          "$.deposit": 32000
        },
        "expect": {
          "$.financedAmount": 0,
          "$.monthlyPayment": 0,
          "$.totalInterest": 0,
          "$.totalCost": 35611.25,
          "$.costPerKm": 0.4748,
          "$.costPerMonth": 593.52
        }
      },
      {
        "description": "the same car as an EV at 17 kWh/100 km and 0.28 per kWh — only the energy line changes",
        "given": {
          "$.fuelType": "ev",
          "$.consumptionPer100": 17,
          "$.unitPrice": 0.28
        },
        "expect": {
          "$.energyCostPerYear": 714,
          "$.totalInterest": 4523.2,
          "$.totalDepreciation": 16320,
          "$.totalCost": 35173.2,
          "$.costPerKm": 0.469,
          "$.depreciationShare": 46.4
        }
      }
    ]
  }
}