MPGe is not MPG, and other ways electric car data misleads
A 2021 Tesla Model 3 reads 134 in the same database field where a Camry reads 32. They are not the same unit, they are not comparable, and neither is the number an EV buyer actually needs.
Last reviewed September 2026
The federal fuel economy database stores an electric car's combined efficiency in exactly the same field as a petrol car's. The values look alike. They measure different things, and a tool that does not know the difference will print a wrong unit on the largest number on the page — which this one did, until recently.
What MPGe actually means
MPGe is miles per gallon equivalent. It takes the energy in one US gallon of petrol — about 33.7 kilowatt-hours — and asks how far the car travels on that much electricity. It is an energy conversion, not a measurement of fuel, and no petrol is involved anywhere in it.
That makes it useful for one job: comparing two electric cars. It is close to useless for comparing an electric car with a petrol one, because the two numbers are answering different questions and the electricity price where you live has no relationship to the pump price the petrol figure assumes.
The three numbers that matter more
For anyone actually choosing an electric car, efficiency is rarely the deciding factor. These are:
| Figure | What it tells you | 2021 Model 3 Long Range |
|---|---|---|
| EPA range | How far on a full charge, tested rather than claimed | 353 miles |
| 240V charge time | An overnight home charge, in hours | 11.2 hours |
| kWh per 100 miles | Consumption — multiply by your tariff for real cost | 25.1 kWh |
- EPA range
- What it tells you:
- How far on a full charge, tested rather than claimed
- 2021 Model 3 Long Range:
- 353 miles
- 240V charge time
- What it tells you:
- An overnight home charge, in hours
- 2021 Model 3 Long Range:
- 11.2 hours
- kWh per 100 miles
- What it tells you:
- Consumption — multiply by your tariff for real cost
- 2021 Model 3 Long Range:
- 25.1 kWh
kWh per 100 miles is the one to learn. Unlike MPGe it converts straight into currency: multiply by your electricity rate and you have the cost of 100 miles. At 25.1 kWh and a rate of $0.15, that is about $3.77 per 100 miles.
Range is a test result, not a promise
The EPA range figure comes from a standard test cycle. Real range moves with cold weather, motorway speed, terrain and how full you charge. Winter figures materially below the label are normal and not a fault.
Note also that within one nameplate the trims differ more than people expect. Across the 2021 Model 3 range: 263 miles for the Standard Range Plus, 353 for the Long Range, 315 for the Performance — with the Performance being both the least efficient (113 MPGe) and the quickest. Efficiency and range are not the same ranking.
Plug-in hybrids are a different animal again
A plug-in hybrid carries two figures because it burns two things. The 2021 Toyota RAV4 Prime is rated 38 MPG on petrol and 94 MPGe on electricity, with 42 miles of electric range and about 600 miles total once the engine is included.
Which number applies to you is decided entirely by whether you plug it in. Seven owners reporting real-world figures average 81.6 MPG — that is a fact about their charging habits, not about the car. Someone with no home charger gets 38 and carries the weight of a battery they never use.
Zero does not always mean zero
A quirk worth knowing if you go to the federal data directly. The EPA fills the electric fields for every vehicle, so a petrol-only 2019 Outback comes back with a range of 0, a charge time of 0.0 and a consumption of 0.0. Those are not measurements — they mean “does not apply”.
Read them literally and you produce a page announcing that a Subaru has zero miles of range and takes zero hours to charge. Meanwhile a genuine zero does exist elsewhere in the same record: an electric car's tailpipe CO2 really is 0.0, and that one is a measurement.
Before you buy
- Work out kWh/100 miles times your own electricity rate, not MPGe.
- Compare the EPA range across trims of the same model — the spread is often 50+ miles.
- Check the 240V charge time against the hours your car is actually parked at home.
- For a plug-in hybrid, settle the charging question before the economy question.
- Assume meaningfully less range in winter than the label.
Official figures for any US-market vehicle are at fueleconomy.gov, which is also where the numbers on this site come from.