# DealScore grade vs KBB value vs CarGurus Deal Rating

A DealScore grade rates one listing's asking price against comparable US dealer listings, the [Kelley Blue Book Fair Market Range](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/) estimates what a consumer can expect to pay a dealer this week in their area for a year, make, and model, and a [CarGurus Deal Rating](https://www.cargurus.com/about/how-cargurus-works) compares a price listed on CarGurus with CarGurus' estimated market value for similar vehicles.

## What it measures

### DealScore grade

- How one listing's asking price compares with an expected price built from comparable US dealer listings. delta_pct is (asking_price minus expected_price) divided by expected_price, and the grade comes from delta_pct alone. (source: [DealScore used car price API](https://cardealscore.com/used-car-price-api), [How DealScore grades work](https://cardealscore.com/guides/how-deal-grades-work))
- A private-party price is judged against dealer prices for comparable cars. (source: [DealScore used car price API](https://cardealscore.com/used-car-price-api))

### Kelley Blue Book Fair Market Range and Fair Purchase Price

- The used-car Fair Market Range is KBB's estimate of what a consumer can reasonably expect to pay this week in their area for a year, make, and model, when buying from a dealer, excluding taxes, title and fees. (source: [KBB: Definitions of our values](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/))
- KBB also publishes separate values for selling: the Trade In Range for trading in at a dealer and the Private Party Value for selling to an individual. (source: [KBB: What's my car worth](https://www.kbb.com/whats-my-car-worth/))

### CarGurus Deal Rating and Instant Market Value (IMV)

- A Deal Rating shows how a listed price compares with CarGurus' estimated market value for similar vehicles, the Instant Market Value (IMV). (source: [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works), [CarGurus Help: What is IMV?](https://cargurus.helpscoutdocs.com/article/10-what-is-imv))
- CarGurus says a Deal Rating reflects price competitiveness only. It is not a certification of condition, reliability, safety, title, accident history, or service quality, and it leaves out taxes, registration, and government fees. (source: [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works))

## Inputs

### DealScore grade

- asking_price and mileage, plus a VIN or year, make, and model. trim and zip are optional. (source: [Connect DealScore to an agent](https://cardealscore.com/agents), [DealScore API reference](https://cardealscore.com/docs/api))

### Kelley Blue Book Fair Market Range and Fair Purchase Price

- Year, make, and model, with typical miles and options or the miles and options the user specifies. kbb.com also accepts a license plate or a VIN. (source: [KBB: Definitions of our values](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/), [KBB: Car values](https://www.kbb.com/car-values/), [KBB: What's my car worth](https://www.kbb.com/whats-my-car-worth/))
- KBB lists its data sources for the range as dealership retail sales transactions, auction sales transactions, economic data, consumer search analytics, online vehicle listings, trade-in marketplace offers, and dealership appraisals. (source: [KBB: Definitions of our values](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/))

### CarGurus Deal Rating and Instant Market Value (IMV)

- IMV comes from comparable vehicle listings and vehicle, listing, and local-market information. That may include make, model, year, trim, mileage, options, location, seller type, vehicle history, and other listing details. (source: [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works))
- The CarGurus car valuation tool takes a license plate or VIN, or make, model, year, and mileage. (source: [CarGurus: Car valuation](https://www.cargurus.com/research/car-valuation))

## Output format

### DealScore grade

- JSON with grade (Great, Good, Fair, High, or Overpriced, or null when it cannot score), score (0 to 100), expected_price with expected_price_low and expected_price_high, delta_pct, confidence, and coverage (scored, partial, or cannot_score). (source: [DealScore used car price API](https://cardealscore.com/used-car-price-api), [How DealScore grades work](https://cardealscore.com/guides/how-deal-grades-work))

### Kelley Blue Book Fair Market Range and Fair Purchase Price

- A dollar range (the Fair Market Range), shown in the KBB Price Advisor, plus the Fair Purchase Price, which is generally the midpoint of the range. (source: [KBB: Vehicle values FAQ](https://b2b.kbb.com/kbb-vehicle-values/faq/), [KBB: Definitions of our values](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/))
- Values are updated weekly and reflect local conditions in over 100 regions. (source: [KBB: Definitions of our values](https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/), [KBB: What's my car worth](https://www.kbb.com/whats-my-car-worth/))

### CarGurus Deal Rating and Instant Market Value (IMV)

- A badge on the listing: Great Deal, Good Deal, Fair Deal, High Price, or Overpriced, or No Deal Rating when there is not enough reliable, comparable, or complete information. (source: [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works))
- IMV is updated daily. Deal Ratings change when price, vehicle details, or market data change, and are not updated second by second. (source: [CarGurus Help: What is IMV?](https://cargurus.helpscoutdocs.com/article/10-what-is-imv), [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works))

## Who it is for

### DealScore grade

- AI agents and the developers who connect them, scoring a listing the user already has. (source: [Connect DealScore to an agent](https://cardealscore.com/agents))

### Kelley Blue Book Fair Market Range and Fair Purchase Price

- Consumers buying or selling a car on kbb.com, and businesses that put KBB values into their own website, mobile app, or loan origination platform. (source: [KBB: What's my car worth](https://www.kbb.com/whats-my-car-worth/), [KBB: InfoDriver Web Service (IDWS)](https://b2b.kbb.com/industry-solutions/info-driver-web-service-idws/))

### CarGurus Deal Rating and Instant Market Value (IMV)

- Car shoppers browsing inventory from participating franchise and independent dealers on CarGurus. CarGurus does not host private-party listings, and browsing is free for buyers. (source: [CarGurus: How CarGurus works](https://www.cargurus.com/about/how-cargurus-works))

## How an agent gets it

### DealScore grade

- MCP at https://cardealscore.com/api/mcp with the tools score_deal, explain_grade, and health, using OAuth or an API key. REST is POST /api/score with an API key. (source: [Connect DealScore to an agent](https://cardealscore.com/agents), [DealScore API reference](https://cardealscore.com/docs/api))
- Free covers 5 scored calls a month. (source: [DealScore pricing](https://cardealscore.com/pricing))

### Kelley Blue Book Fair Market Range and Fair Purchase Price

- InfoDriver Web Service (IDWS), a REST-compatible service with VIN decode and documentation on a developer portal. Its values include the Used Car Fair Market Range, Fair Purchase Price, Private Party Value and Range, and Trade-in Value and Range. (source: [KBB: InfoDriver Web Service (IDWS)](https://b2b.kbb.com/industry-solutions/info-driver-web-service-idws/))

### CarGurus Deal Rating and Instant Market Value (IMV)

- A CarGurus MCP connector in the Claude connector directory and the ChatGPT plugin store. It searches US vehicle listings and retrieves vehicle details, is read-only, needs no CarGurus login, and returns up to 20 listings per search. (source: [CarGurus Help: Connect AI assistants with the MCP connector](https://cargurus.helpscoutdocs.com/article/599-connect-ai-assistants-to-cargurus-with-the-mcp-connector))

## Sources

- KBB: Definitions of our values: https://b2b.kbb.com/kbb-vehicle-values/definitions-of-our-values/ (as of 2026-10-23)
- KBB: Vehicle values FAQ: https://b2b.kbb.com/kbb-vehicle-values/faq/ (as of 2026-10-23)
- KBB: InfoDriver Web Service (IDWS): https://b2b.kbb.com/industry-solutions/info-driver-web-service-idws/ (as of 2026-10-23)
- KBB: Car values: https://www.kbb.com/car-values/ (as of 2026-10-23)
- KBB: What's my car worth: https://www.kbb.com/whats-my-car-worth/ (as of 2026-10-23)
- CarGurus: How CarGurus works: https://www.cargurus.com/about/how-cargurus-works (as of 2026-10-23)
- CarGurus: Car valuation: https://www.cargurus.com/research/car-valuation (as of 2026-10-23)
- CarGurus Help: What is IMV?: https://cargurus.helpscoutdocs.com/article/10-what-is-imv (as of 2026-10-23)
- CarGurus Help: Connect AI assistants with the MCP connector: https://cargurus.helpscoutdocs.com/article/599-connect-ai-assistants-to-cargurus-with-the-mcp-connector (as of 2026-10-23)
- DealScore API reference: https://cardealscore.com/docs/api (as of 2026-10-23)
- DealScore used car price API: https://cardealscore.com/used-car-price-api (as of 2026-10-23)
- How DealScore grades work: https://cardealscore.com/guides/how-deal-grades-work (as of 2026-10-23)
- Connect DealScore to an agent: https://cardealscore.com/agents (as of 2026-10-23)
- DealScore pricing: https://cardealscore.com/pricing (as of 2026-10-23)

Only facts stated on each company's own pages are listed. Where a page does not say something, this guide leaves it out.

## Quick answers

### What does a DealScore grade measure?

How one listing's asking price compares with an expected price built from comparable US dealer listings. delta_pct is (asking_price minus expected_price) divided by expected_price, and the grade comes from delta_pct alone. A private-party price is judged against dealer prices for comparable cars.

### What does DealScore need to grade a car?

asking_price and mileage, plus a VIN or year, make, and model. trim and zip are optional.

### What does a DealScore grade return?

JSON with grade (Great, Good, Fair, High, or Overpriced, or null when it cannot score), score (0 to 100), expected_price with expected_price_low and expected_price_high, delta_pct, confidence, and coverage (scored, partial, or cannot_score).

### How does an agent get a DealScore grade?

MCP at https://cardealscore.com/api/mcp with the tools score_deal, explain_grade, and health, using OAuth or an API key. REST is POST /api/score with an API key. Free covers 5 scored calls a month.

## Get a DealScore grade

To get a DealScore grade from an agent, connect the MCP server or create an API key. Free covers 5 scored calls a month.

- Connect over MCP: https://cardealscore.com/agents
- Sign in to create an API key: https://cardealscore.com/login?next=%2Fkeys
- Pricing: https://cardealscore.com/pricing