Our methodology
How the GreenCars Score works
What we measure
Three scores, one rating
Each vehicle gets its own Affordability, Performance, and Sustainability score on the same 1 to 10 scale. The GreenCars Score blends the three.
Affordability
What it really costs to buy and own.
- Purchase price
- Estimated monthly loan payment
- Monthly fuel or charging cost
- How well it's expected to hold its value
- How its price compares with similar vehicles
Price is compared within peer groups too, so a vehicle isn't penalized just for belonging to a pricier category.
Performance
How it drives and how far it goes.
- Total driving range
- Efficiency (MPG, or MPGe for plug-ins)
- 0 to 60 mph acceleration
- How recent the model year is
- For plug-ins: Level 2 (240V) charging time and battery capacity
Efficiency is compared like with like: plug-ins against other plug-ins on MPGe, and gas and hybrid vehicles against each other on MPG.
Sustainability
Its impact on the air we breathe.
- Tailpipe CO₂ emissions
- EPA Smog Rating
Vehicles with zero tailpipe emissions, such as fully electric models, receive full marks for CO₂.
How it's built
From raw data to a score
Step 1: Gather verified data
We pull official EPA fuel economy and emissions figures, manufacturer specifications, and current pricing for each trim. Records that don't line up cleanly go to our team for review.
Step 2: Compare against the market
Each measurement is ranked against the same measurement for the other vehicles in our Buyers Guide. A vehicle earns more points the better it ranks.
Step 3: Score each area
The rankings within each area combine into the Affordability, Performance, and Sustainability scores, each from 1 to 10.
Step 4: Blend into one rating
The three scores are weighted and combined into the GreenCars Score. Our team sets and periodically reviews those weights.
Reading the score
A relative score, not a pass or fail
The GreenCars Score tells you where a vehicle stands against today's market. A 10 means a vehicle is at or near the top of the vehicles we cover. It doesn't mean the vehicle is perfect.
Because the comparison is to the current market, a score can shift as new models arrive and prices change, even if nothing about the vehicle itself changed.
| Score | What it means |
|---|---|
| 8.0–10 | Excellent. Among the strongest vehicles we cover. |
| 6.5–7.9 | Highly rated. Clearly better than most. |
| 5.0–6.4 | Good. Solid, with some trade-offs. |
| 3.5–4.9 | Fair. Trails the market in one or more areas. |
| Below 3.5 | Below average. Behind most comparable vehicles. |
Our ground rules
What keeps the score fair
One method for every vehicle
Every vehicle is scored by the same automated process, from the same data sources, regardless of brand or powertrain.
No data, no score
We only publish a score when we have every data point it needs. If something is missing, we leave the score off rather than guess.
Kept current
Scores are recalculated each day as our data refreshes, so they reflect today's prices and today's lineup.
Scored by trim
Each trim is scored on its own. The headline score on a model page is the average of that model year's trims.
Where the data comes from
Sources we rely on
- U.S. Environmental Protection Agency
- Fuel economy (MPG and MPGe), electric range, tailpipe CO₂, and Smog Ratings, from the EPA's official data published at fueleconomy.gov (opens in a new tab).
- Manufacturer specifications
- Acceleration, battery capacity, charging times, and other specifications for each trim, from industry vehicle data and manufacturer-published figures.
- Market pricing
- Manufacturer's suggested retail prices and current market prices, which feed the price, payment, and value-retention estimates.
- National averages
- Average fuel and electricity prices, typical annual mileage, and typical loan terms, so cost estimates are comparable from one vehicle to the next.
Questions
Frequently asked questions
Is a 10 a perfect car?
No. The GreenCars Score is relative. A 10 means a vehicle ranks at or near the top of the vehicles in our Buyers Guide, not that it has no weaknesses.
Can I compare a gas car with an electric car?
Yes. Every vehicle is scored on the same 1 to 10 scale. Where a measurement only makes sense within a powertrain, such as MPG versus MPGe, we compare like with like before rolling it into the score.
Why did a vehicle's score change?
Scores are recalculated as our data refreshes. A new model arriving, a price change, or corrected specifications can all move a score, because each vehicle is measured against the current market.
Why doesn't every vehicle have a score?
We only publish a score when we have every data point the score needs. If something is missing, we leave the score off rather than estimate it.
Do you publish the exact formula?
We publish what goes into the score and how it is built, but not the exact weights. Keeping those private helps keep the score from being gamed.