Every window sticker carries a fuel economy score out of ten. It looks like a verdict on the car, and buyers read it that way — a 7 is good, a 4 is not.
It is not a verdict on the car. It is a verdict on the car relative to everything else certified that year, and the comparison set does not stand still.
| Period | Score given to a 25 mpg vehicle | Records |
|---|---|---|
| 2010-2014 | 6.43 | 374 |
| 2015-2019 | 5.41 | 1,168 |
| 2020-2024 | 5.07 | 1,031 |
| 2025- | 5.09 | 270 |
Same consumption, same test, 1.3 points lower. The car did not change — the field around it did.
The scale is anchored to the market, not to physics
Watch what happens to the average score as the fleet improves.
| Period | Average certified mpg | Average score |
|---|---|---|
| 2010-2014 | 23.3 | 5.37 |
| 2015-2019 | 25.1 | 5.05 |
| 2020-2024 | 29.8 | 5.10 |
| 2025- | 42.0 | 5.87 |
Certified consumption almost doubled — 23.3 to 42.0 mpg. The average score moved half a point.
That is the design working as intended. A relative scale keeps its midpoint near the middle of the market, so the number tells you where a car sits among its contemporaries rather than what it consumes.
Useful for comparing two cars in a showroom in the same year. Actively misleading for comparing a used 2012 car against a used 2024 one, which is exactly what a second-hand buyer does.
What each score actually consumes
Since the scale moves, the only way to read it is against the underlying figures.
| Score | Average mpg | Average annual fuel cost |
|---|---|---|
| 1 | 12.7 | $5,834 |
| 3 | 17.2 | $4,136 |
| 5 | 23.5 | $3,042 |
| 7 | 30.1 | $2,266 |
| 8 | 34.4 | $2,032 |
| 10 | 89.8 | $884 |
The jump between 8 and 9 is where the scale stops describing petrol engines. Records scoring 8 average 34.4 mpg; records scoring 9 average 77.0. Nothing with a combustion engine sits in that gap, because the top two points are effectively reserved for electrified powertrains measured in mpg-equivalent.
So a score of 8 is the practical ceiling for a petrol car, and comparing it against a 10 is comparing two different measurement systems.
How to use the sticker properly
Within one model year, the score does what it claims: it ranks the car against its competition, and a 7 genuinely beats a 5.
Across model years, ignore it and read the mpg. That number is absolute, measured by the same procedure, and comparable in a way the score is not.
And for a used purchase the annual cost column is the one that matters, because it converts the whole thing into money at a stroke. The difference between a score of 5 and a score of 7 is roughly $780 a year — which over five years of ownership exceeds most of the price differences buyers argue about.
What the sticker cannot tell you is what has happened to the specific car since it was certified. A free VIN check covers that half.
Frequently asked questions
What is the fuel economy score on a window sticker?
A 1-to-10 rating comparing that vehicle's fuel consumption against the rest of the market. It is relative rather than absolute, which means the same consumption earns a different score depending on when the car was certified — 25 mpg scored 6.43 on average in 2010-2014 and 5.07 in 2020-2024.
Why does the average score stay near 5 while fuel economy improves?
Because the scale is recalibrated against the current market. Average certified consumption rose from 23.3 mpg in 2010-2014 to 42.0 mpg in 2025-onward records, yet the average score moved only from 5.37 to 5.87. The midpoint follows the fleet.
Can I compare scores between a 2012 car and a 2024 car?
Not directly, and this is the practical trap. A 2012 car showing 7 and a 2024 car showing 7 do not consume the same fuel — the older one is measured against an easier field. Compare the mpg figures instead, which are absolute.
What does a score of 9 or 10 mean now?
Almost always an electric or plug-in vehicle. Records scoring 9 average 77 mpg-equivalent and those scoring 10 average 89.8 — figures no petrol engine reaches. The top of the scale has effectively been reserved for electrified powertrains.
Denis Kataev is a serial solopreneur and the founder of ForCar. With 15+ years in software engineering and 10 years in SEO, he builds data-driven products end to end — backed by a sharp eye for design. At ForCar he mines proprietary vehicle datasets, turning raw numbers into buying advice you can actually trust.
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