# FuelEconomy.gov API

> FuelEconomy.gov returns vehicle fuel economy ratings, driving range, costs, and emissions as a workflow and API.

FuelEconomy.gov’s Get fuel economy returns MPG or MPGe, range, costs, savings, and emissions for a make, year, and model. Compare cars returns fuel economy and annual fuel costs for two to four cars entered by year, make, and model.

- Page: https://fous.com/workflows/fueleconomy-gov
- Handle: `@fueleconomy-gov`
- Category: [Energy](https://fous.com/workflows/category/energy)
- Source website: https://fueleconomy.gov
- Last verified: Sep 29, 2026
- Fous is not affiliated with FuelEconomy.gov.

## Methods

### Compare cars

Operation `compare_cars`, version 1. 1 credit per call.

Compare the official fuel economy and annual fuel costs of two to four cars by year, make and model. Selects a base version when no trim is specified; annual costs use FuelEconomy.gov estimates and plug-in hybrid figures may vary with charging.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `cars` | array | yes |  | Two to four cars, each with a year, make, and model; for example, 2024 Toyota Camry Hybrid and 2024 Tesla Model 3. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "cars"
  ],
  "properties": {
    "cars": {
      "type": "array",
      "items": {
        "type": "string",
        "minLength": 6,
        "examples": [
          "2024 Toyota Camry Hybrid",
          "2024 Tesla Model 3",
          "2024 Honda Civic"
        ],
        "description": "Use the same format as these example values: \"2024 Toyota Camry Hybrid\", \"2024 Tesla Model 3\", \"2024 Honda Civic\"."
      },
      "maxItems": 4,
      "minItems": 2,
      "description": "Two to four cars, each with a year, make, and model; for example, 2024 Toyota Camry Hybrid and 2024 Tesla Model 3.",
      "examples": [
        [
          "2024 Toyota Camry Hybrid",
          "2024 Tesla Model 3"
        ],
        [
          "2024 Honda Civic",
          "2024 Toyota Camry",
          "2024 Toyota Prius Prime",
          "2024 Madeup Phantom"
        ]
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "cars": [
        "2024 Toyota Camry Hybrid",
        "2024 Tesla Model 3"
      ]
    },
    {
      "cars": [
        "2024 Honda Civic",
        "2024 Toyota Camry",
        "2024 Toyota Prius Prime",
        "2024 Madeup Phantom"
      ]
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `cars` | array |  | Vehicle comparisons in the order entered. |
| `cars[].car` | string | `"2024 Toyota Camry Hybrid"` | Car exactly as entered. |
| `cars[].city` | number or null | `51` | City fuel economy in the stated unit. |
| `cars[].link` | string or null | `"https://www.fueleconomy.gov/feg/noframes/47092.shtml"` | FuelEconomy.gov page for the matched vehicle. |
| `cars[].note` | string or null |  | Why the car could not be matched, when applicable. |
| `cars[].highway` | number or null | `53` | Highway fuel economy in the stated unit. |
| `cars[].combined` | number or null | `52` | Combined fuel economy in the stated unit. |
| `cars[].fuel_type` | string or null | `"Regular"` | Fuel used by the vehicle. |
| `cars[].vehicle_id` | string or null | `"47092"` | FuelEconomy.gov vehicle ID. |
| `cars[].efficiency_unit` | string or null | `"MPG"` | MPG or MPGe for the fuel economy figures. |
| `cars[].vehicle_matched` | string or null | `"2024 Toyota Camry Hybrid LE — Auto (AV-S6), 4 cyl, 2.5 L"` | Official vehicle version selected, including transmission and engine. |
| `cars[].co2_grams_per_mile` | number or null | `170` | Tailpipe carbon dioxide emissions in grams per mile. |
| `cars[].annual_fuel_cost_usd` | number or null | `1250` | Estimated annual fuel cost in US dollars. |
| `cars[].electric_range_miles` | number or null | `272` | Electric-only driving range in miles, when available. |
| `cars[].greenhouse_gas_score` | integer or null | `8` | Greenhouse gas score from 1 to 10. |
| `summary` | string | `"2024 Tesla Model 3 RWD — Auto (A1) is the cheapest to run, saving $700 per year versus 2024 Toyota Camry Hybrid LE — Au` | Cheapest vehicle to run and annual savings over the most expensive. |

**Example input**

```json
{
  "cars": [
    "2024 Toyota Camry Hybrid",
    "2024 Tesla Model 3"
  ]
}
```

**Example output**

```json
{
  "cars": [
    {
      "car": "2024 Toyota Camry Hybrid",
      "city": 51,
      "link": "https://www.fueleconomy.gov/feg/noframes/47092.shtml",
      "note": null,
      "highway": 53,
      "combined": 52,
      "fuel_type": "Regular",
      "vehicle_id": "47092",
      "efficiency_unit": "MPG",
      "vehicle_matched": "2024 Toyota Camry Hybrid LE — Auto (AV-S6), 4 cyl, 2.5 L",
      "co2_grams_per_mile": 170,
      "annual_fuel_cost_usd": 1250,
      "electric_range_miles": null,
      "greenhouse_gas_score": 8
    },
    {
      "car": "2024 Tesla Model 3",
      "city": 140,
      "link": "https://www.fueleconomy.gov/feg/noframes/47909.shtml",
      "note": null,
      "highway": 125,
      "combined": 132,
      "fuel_type": "Electricity",
      "vehicle_id": "47909",
      "efficiency_unit": "MPGe",
      "vehicle_matched": "2024 Tesla Model 3 RWD — Auto (A1)",
      "co2_grams_per_mile": 0,
      "annual_fuel_cost_usd": 550,
      "electric_range_miles": 272,
      "greenhouse_gas_score": 10
    }
  ],
  "summary": "2024 Tesla Model 3 RWD — Auto (A1) is the cheapest to run, saving $700 per year versus 2024 Toyota Camry Hybrid LE — Auto (AV-S6), 4 cyl, 2.5 L."
}
```

### Get fuel economy

Operation `get_fuel_economy`, version 1. 1 credit per call.

Get official MPG or MPGe, driving range, annual fuel cost, five-year savings, and emissions for all matching vehicle versions. Fuel costs use current fuel prices and EPA’s 15,000-mile-per-year assumption; plug-in hybrid costs include gasoline and electricity.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `make` | string | yes | `"Toyota"` | Vehicle make, for example Toyota. |
| `year` | integer | yes | `2022` | Model year, for example 2022. |
| `model` | string | yes | `"RAV4"` | Model name, for example RAV4 or Model 3. |
| `version` | string | no | `"Hybrid AWD"` | Optional words identifying trim, engine, transmission or drive, for example Hybrid AWD. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "year",
    "make",
    "model"
  ],
  "properties": {
    "make": {
      "type": "string",
      "description": "Vehicle make, for example Toyota.",
      "examples": [
        "Toyota",
        "Tesla"
      ]
    },
    "year": {
      "type": "integer",
      "description": "Model year, for example 2022.",
      "examples": [
        2022
      ]
    },
    "model": {
      "type": "string",
      "description": "Model name, for example RAV4 or Model 3.",
      "examples": [
        "RAV4",
        "Model 3",
        "Prius Prime"
      ]
    },
    "version": {
      "type": "string",
      "default": "",
      "description": "Optional words identifying trim, engine, transmission or drive, for example Hybrid AWD.",
      "examples": [
        "Hybrid AWD"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "make": "Toyota",
      "year": 2022,
      "model": "RAV4",
      "version": "Hybrid AWD"
    },
    {
      "make": "Tesla",
      "year": 2022,
      "model": "Model 3"
    },
    {
      "make": "Toyota",
      "year": 2022,
      "model": "Prius Prime"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `versions` | array |  | Matching official vehicle versions. |
| `versions[].make` | string | `"Toyota"` | Make. |
| `versions[].year` | integer | `2022` | Model year. |
| `versions[].drive` | string or null | `"All-Wheel Drive"` | Drive type. |
| `versions[].model` | string | `"RAV4 Hybrid AWD"` | Full model and trim name. |
| `versions[].engine` | string or null | `"2.5 L, 4 cylinders, SIDI & PFI; Hybrid"` | Engine or electric motor. |
| `versions[].city_mpg` | number or null | `41` | City miles per gallon on liquid fuel. |
| `versions[].page_url` | string | `"https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=45009"` | FuelEconomy.gov vehicle page. |
| `versions[].city_mpge` | number or null | `134` | City miles per gallon gasoline equivalent for electric driving. |
| `versions[].fuel_type` | string | `"Regular"` | Vehicle fuel type. |
| `versions[].vehicle_id` | string | `"45009"` | FuelEconomy.gov vehicle ID. |
| `versions[].highway_mpg` | number or null | `38` | Highway miles per gallon on liquid fuel. |
| `versions[].range_miles` | number or null | `358` | Electric vehicle range in miles. |
| `versions[].combined_mpg` | number or null | `40` | Combined miles per gallon on liquid fuel. |
| `versions[].highway_mpge` | number or null | `126` | Highway miles per gallon gasoline equivalent for electric driving. |
| `versions[].transmission` | string or null | `"Automatic (AV-S6)"` | Transmission. |
| `versions[].combined_mpge` | number or null | `131` | Combined miles per gallon gasoline equivalent for electric driving. |
| `versions[].fuel_price_unit` | string or null | `"gallon"` | Fuel price unit, such as gallon or kWh. |
| `versions[].co2_grams_per_mile` | number or null | `223` | Tailpipe CO2 emissions in grams per mile. |
| `versions[].vehicle_description` | string | `"2022 Toyota RAV4 Hybrid AWD, 2.5 L, 4 cylinders, SIDI & PFI; Hybrid, Automatic (AV-S6), All-Wheel Drive"` | Vehicle year, make, model, engine, transmission and drive. |
| `versions[].annual_fuel_cost_usd` | number or null | `1600` | Official annual fuel cost in US dollars. |
| `versions[].annual_miles_assumed` | integer | `15000` | Annual mileage used to calculate fuel cost. |
| `versions[].electric_range_miles` | number or null | `25` | Plug-in hybrid electric range in miles. |
| `versions[].greenhouse_gas_score` | integer or null | `8` | EPA greenhouse gas score from 1 to 10. |
| `versions[].five_year_savings_usd` | number or null | `3500` | Five-year fuel cost savings versus the average new vehicle in US dollars; negative means extra cost. |
| `versions[].fuel_price_usd_per_unit` | number or null | `4.32` | Current fuel price in US dollars per stated unit. |
| `versions[].secondary_fuel_price_unit` | string or null | `"kWh"` | Unit for secondary fuel price. |
| `versions[].secondary_fuel_price_usd_per_unit` | number or null | `0.15` | Electricity or other alternative fuel price for dual-fuel vehicles. |

**Example input**

```json
{
  "make": "Toyota",
  "year": 2022,
  "model": "RAV4",
  "version": "Hybrid AWD"
}
```

**Example output**

```json
{
  "versions": [
    {
      "make": "Toyota",
      "year": 2022,
      "drive": "All-Wheel Drive",
      "model": "RAV4 Hybrid AWD",
      "engine": "2.5 L, 4 cylinders, SIDI & PFI; Hybrid",
      "city_mpg": 41,
      "page_url": "https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=45009",
      "city_mpge": null,
      "fuel_type": "Regular",
      "vehicle_id": "45009",
      "highway_mpg": 38,
      "range_miles": null,
      "combined_mpg": 40,
      "highway_mpge": null,
      "transmission": "Automatic (AV-S6)",
      "combined_mpge": null,
      "fuel_price_unit": "gallon",
      "co2_grams_per_mile": 223,
      "vehicle_description": "2022 Toyota RAV4 Hybrid AWD, 2.5 L, 4 cylinders, SIDI & PFI; Hybrid, Automatic (AV-S6), All-Wheel Drive",
      "annual_fuel_cost_usd": 1600,
      "annual_miles_assumed": 15000,
      "electric_range_miles": null,
      "greenhouse_gas_score": 8,
      "five_year_savings_usd": 3500,
      "fuel_price_usd_per_unit": 4.32,
      "secondary_fuel_price_unit": null,
      "secondary_fuel_price_usd_per_unit": null
    }
  ]
}
```

## Quick start

Call the API with a Fous API key (`FOUS_API_KEY`). To create one, turn on Developer mode in Fous Studio, then open Keys & connections → API keys (https://app.fous.com/keys).

```bash
# First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
: "${FOUS_API_KEY:?Set FOUS_API_KEY before running this example}"

curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 120 \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@fueleconomy-gov",
  "visibility": "public",
  "operation": "compare_cars",
  "version": 1,
  "input": {
    "cars": [
      "2024 Toyota Camry Hybrid",
      "2024 Tesla Model 3"
    ]
  },
  "response": {
    "format": "json"
  }
}'
```

```python
# Save as fous.py and run with python3 fous.py. No packages needed.
# First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
import json
import os
import urllib.error
import urllib.request

api_key = os.environ.get("FOUS_API_KEY")
if not api_key:
    raise RuntimeError("Set FOUS_API_KEY before running this example")

body = json.loads("{\n  \"api\": \"@fueleconomy-gov\",\n  \"visibility\": \"public\",\n  \"operation\": \"compare_cars\",\n  \"version\": 1,\n  \"input\": {\n    \"cars\": [\n      \"2024 Toyota Camry Hybrid\",\n      \"2024 Tesla Model 3\"\n    ]\n  },\n  \"response\": {\n    \"format\": \"json\"\n  }\n}")
request = urllib.request.Request(
    "https://api.fous.com/v1/query",
    data=json.dumps(body).encode("utf-8"),
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    method="POST",
)
try:
    with urllib.request.urlopen(request, timeout=120) as response:
        result = json.load(response)
except urllib.error.HTTPError as error:
    raise RuntimeError(f"HTTP {error.code}: {error.read().decode('utf-8', errors='replace')}") from error
if result.get("success") is False:
    raise RuntimeError(result.get("error", {}).get("message", "Request failed"))
print(json.dumps(result["data"]["output"], indent=2))
```

```typescript
// Save as fous.mts and run with npx tsx fous.mts.
// First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
const apiKey = process.env.FOUS_API_KEY;
if (!apiKey) throw new Error("Set FOUS_API_KEY before running this example");

const response = await fetch("https://api.fous.com/v1/query", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  signal: AbortSignal.timeout(120_000),
  body: JSON.stringify({
  "api": "@fueleconomy-gov",
  "visibility": "public",
  "operation": "compare_cars",
  "version": 1,
  "input": {
    "cars": [
      "2024 Toyota Camry Hybrid",
      "2024 Tesla Model 3"
    ]
  },
  "response": {
    "format": "json"
  }
}),
});
type ApiResult = { success: boolean; data?: { output: unknown }; error?: { message: string } };
const result: ApiResult = await response.json();
if (!response.ok || result.success === false) {
  throw new Error(result.error?.message ?? `HTTP ${response.status}`);
}
if (!result.data) throw new Error("Missing API response data");
console.log(result.data.output);
```

Or describe the data in plain language: send `{"api":"@fueleconomy-gov","prompt":"Describe the data you need, with every detail"}` to the same URL. Fous fills in the input, runs the method that fits and returns only the fields you asked for; `data.route.calls[].request` is the exact call it made. Routing is free; the run costs the same.

## Use cases

- Compare fuel costs across vehicle options
- Identify vehicles with longer electric driving range
- Review emissions and greenhouse gas scores
- Estimate annual fuel costs for a vehicle
- Find fuel economy ratings for a specific trim

## FAQ

### Is Fous affiliated with FuelEconomy.gov?

No. Fous is not affiliated with FuelEconomy.gov. This workflow reads the public fueleconomy.gov website and returns its data.

### How much does it cost?

Each run costs 1 credit. With pay-as-you-go, a credit costs 1¢; monthly plans cost less per credit.

### Do I need a FuelEconomy.gov account?

No. You only need a Fous account.

### How current is the data?

Fous gets the data from fueleconomy.gov when you run it; repeating the same request within a day may return the saved result. Fous checks this workflow automatically; it last passed a check on Sep 29, 2026.

### What is a vehicle’s city, highway, and combined fuel economy?

Get fuel economy returns city, highway, and combined MPG or MPGe for matching versions. Compare cars provides these figures for two to four cars.

### What is a vehicle’s electric driving range?

Get fuel economy returns electric range for matching versions; Compare cars provides electric-only range when available.

### How do annual fuel costs compare between cars?

Compare cars returns estimated annual fuel costs and summarizes the cheapest vehicle and its annual savings over the most expensive.

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