MPG for vehicles means miles per gallon, the standard UK measure of how far a petrol or diesel vehicle travels on one imperial gallon of fuel. A registration lookup does not usually show an MPG figure, because the Driver and Vehicle Licensing Agency (DVLA) record holds fuel type, engine capacity and CO2 emissions rather than fuel economy. Those three details are enough to narrow down a vehicle's likely efficiency, and the official figure comes from the manufacturer's type approval data.
Part of DVLA Vehicle Details. Start with the main guide: Car Spec Check by Registration
Updated October 2026 · Independent information, not legal advice
If you are comparing cars, estimating running costs or working out what an old van really drinks, the registration is still the best starting point. Confirm what the vehicle is, then use the right source for the fuel economy number. Below is what each source can and cannot tell you, plus how to calculate your own real-world MPG.
Can I Check MPG By Registration?
You can check mpg by reg only indirectly: a lookup confirms the exact make, model, fuel type and engine size, and that tells you which official fuel economy figure to look up.
What the lookup does return
The free number plate check shows the fuel type, engine capacity, year of manufacture, CO2 emissions and Euro status where recorded, plus MOT and tax status.
What it does not return
It does not show miles per gallon, litres per 100 km, a trim level or a gearbox type. Two cars with the same engine can have different official economy figures.
What Is The MPG Of My Car By Registration?
The mpg of my car by registration is not stored in a single public record, but it can be found by matching the registration to a model, then reading the official figure for that exact version.
The three-step method
- Look up the registration to confirm make, model and fuel type.
- Note the engine capacity and the year of first registration.
- Find the official combined figure for that version in the manufacturer's data or the government's fuel consumption database.
Why the exact version matters
Engine variants, tyre sizes and gearboxes change the result, so a general "model average" can be off.
How Do I Check Car Fuel Economy Properly?
To check car fuel economy, use official test figures for comparison and your own fill-up records for reality.
- Official figures come from laboratory tests of the model.
- Your own figures come from miles driven between full tanks.
- On-board computers estimate economy but can read optimistic.
- Fuel card or app logs give a long-run average.
Official versus real-world
Test figures are a comparison tool. In everyday driving, traffic, weather, load, tyre pressure and driving style usually push real economy away from the lab figure.
How Do I Check Fuel Type By Reg?
To check fuel type by reg, enter the registration; the lookup shows petrol, diesel, electric, hybrid or another fuel recorded on the DVLA record.
Why fuel type matters before you fill up
Putting the wrong fuel in a car can cause expensive damage. If you have just bought a vehicle, confirm the fuel type with a lookup before the first fill.
Hybrids and plug-ins
A hybrid or plug-in hybrid may show as one fuel type on the record, while real use combines petrol and electricity. Check the manufacturer's data for the combined range.
What Does CO2 Emissions Tell Me About MPG?
CO2 emissions in grams per kilometre are closely linked to fuel consumption for petrol and diesel vehicles: lower CO2 usually means better economy.
Using CO2 as a rough guide
If you cannot find an MPG figure, compare CO2 emissions across similar cars. The lower figure normally uses less fuel, though petrol and diesel are not directly comparable.
The tax link
The same figure can affect vehicle excise duty for cars registered in the relevant period. See CO2 emissions checker by reg for how it is recorded.
How Does Engine Size Relate To Fuel Economy?
Engine capacity, shown in cc or litres, gives a hint but not an answer.
- Smaller engines often use less fuel in light use.
- Turbochargers let small engines work hard under load.
- Weight and aerodynamics matter as much as engine size.
- Gearing and hybrid systems can outweigh the cc figure.
A common myth
"A small engine is always cheap to run" is not guaranteed. A small engine pushed hard in a heavy van may use more fuel than a larger engine cruising.
UK Mpg Versus US Mpg
A UK or imperial gallon is 4.546 litres, which is larger than a US gallon, so UK mpg figures look higher than US figures for the same car.
| Measure | Used for | Notes |
|---|---|---|
| mpg (UK) | Petrol, diesel, hybrid | Miles per imperial gallon, used on UK sales material |
| mpg (US) | Imported or foreign data | Smaller gallon, so numbers are lower |
| L/100 km | Many manufacturer sheets | Lower is better |
| mi/kWh | Electric cars | Miles per unit of electricity |
| MPGe | Comparing electric with petrol | An equivalence, not a real fuel measure |
Converting L/100 km to mpg
Divide 282.5 by the litres per 100 km figure to get UK mpg. For example, 5.0 litres per 100 km is about 56 mpg.
How Do I Work Out My Own MPG?
Working out my own mpg takes only a full tank and a note of the odometer.
- Fill the tank to the pump cut-off and note the odometer.
- Drive as normal and refill to the cut-off next time.
- Note the litres added and the miles driven.
- Divide the litres by 4.546 to get gallons, then divide miles by gallons.
Why repeat it
One tank can mislead. Repeat the calculation a few times and take an average.
Can MOT History Help Estimate Fuel Use?
The MOT history records odometer readings at every test, so you can see annual mileage. Combined with fuel receipts, you can estimate economy over a year. Look at the MOT history for dates and readings.
Mileage as a sanity check
A mileage that suddenly drops between tests is a red flag; see mileage check.
What About Electric Vehicles?
Electric cars do not use petrol, so MPG is not the right measure. Efficiency is given in miles per kWh and range in miles.
Checking range
Official range figures come from the manufacturer's data. Real range varies with temperature, speed and battery age.
Zero tailpipe emissions
Electric cars show zero CO2 emissions on the record. Tax rules for them change over time, so confirm the current position on GOV.UK.
Motorbikes And Mopeds
Motorcycles are usually quoted in mpg or litres per 100 km, and lookups show their engine capacity in cc. See motorcycle road tax for how engine size relates to tax.
Small capacity advantage
A small-capacity bike generally burns less fuel than a large tourer, but riding style and load still matter.
Vans, Trucks And Motorhomes
Commercial vehicles are often described by gross weight and payload, and fuel economy depends heavily on load.
Fleet fuel tracking
Fleet owners often log fuel by registration so that unusual consumption stands out. A sudden jump may signal a mechanical fault or fuel misuse.
- Record the odometer at every fill.
- Log fuel by registration, not by driver alone.
- Compare similar vehicles on similar routes.
- Investigate a sharp change before it becomes a repair bill.
Does The V5C Show Fuel Economy?
No. The V5C (the registration certificate, or logbook) lists fuel type, engine size and CO2 emissions but not mpg. The registered keeper named on it is not necessarily the legal owner.
Where else to find the figure
Look in the handbook, the manufacturer's website or the government fuel consumption database for the exact model version.
Why Is My Real MPG Lower Than Advertised?
Test conditions are controlled and rarely match your journeys, so real economy is usually below the published figure.
Common drains
- Short trips in cold weather.
- Under-inflated tyres.
- Roof boxes and extra weight.
- Heavy acceleration and high speed.
- Air-conditioning use.
- Worn spark plugs or a dirty air filter.
Can an MOT fail for emissions?
The MOT includes an emissions test, and an engine running badly can fail it. See what fails an MOT.
How Do I Use The Registration When Buying A Used Car?
Use a lookup to confirm that the car's fuel type, engine capacity and year match the advert, then compare official fuel figures for that version before agreeing.
Spotting mismatches
If the advert says diesel and the lookup says petrol, ask questions. An engine swap is not necessarily a problem but it should be disclosed and documented.
Northern Ireland And Imports
The same fuel figures apply to Northern Ireland vehicles, though testing is run by the DVA. Imported vehicles may have US or Japanese figures that use different test cycles, so check the UK type approval.
Grey imports
An import with no UK figures needs the manufacturer's or approval body's data. Do not assume the foreign figure applies.
Common Mistakes With MPG Figures
Avoid these pitfalls.
- Mixing US and UK mpg.
- Treating the combined figure as a promise.
- Using the average for a model instead of the exact version.
- Ignoring that fuel type changes the cost per mile.
A simple rule
Use official figures to compare cars and your own fill-up data to budget.
Where The Official Data Lives
The DVLA Vehicle Enquiry Service on GOV.UK gives vehicle details and CO2 emissions; the government's fuel consumption database lists official economy figures by model. See car spec check for what a registration can reveal.
Frequently Asked Questions
Can I check MPG by reg?
Not directly. A registration lookup shows the make, model, fuel type, engine capacity, year of manufacture and CO2 emissions where recorded, but not miles per gallon. Use that information to find the official fuel consumption figure for the exact version in the manufacturer's data or the government's fuel consumption database.
What is the mpg of my car by registration?
Look up the registration to confirm the make, model, fuel type and engine size. Then find the official combined figure for that version in the handbook, the maker's website or the government's database. The figure is a test result, so your own driving will usually be lower.
How do I check car fuel economy?
For comparison, use the official test figure for your exact version. For reality, fill the tank, note the odometer, drive normally, refill and divide the miles by the gallons used. Repeat over several tanks and average the results for a more reliable number.
How do I check fuel type by reg?
Enter the registration into the free lookup. The fuel type shown is taken from the DVLA vehicle record, such as petrol, diesel or electric. Hybrids may appear under one type, so also check the manufacturer's data for the combined system.
Does the V5C show MPG?
No. The V5C registration certificate shows details such as fuel type, engine size, CO2 emissions, colour and the registered keeper, but it does not record fuel consumption. The handbook or the manufacturer's data is the right source.
Is UK mpg the same as US mpg?
No. A UK gallon is 4.546 litres, larger than a US gallon, so a UK mpg figure is higher than a US mpg figure for the same car. When reading imported specifications, check which gallon is used before comparing.
How do I convert litres per 100 km to mpg?
Divide 282.5 by the litres per 100 km figure to get miles per UK gallon. For instance, 8 litres per 100 km works out at roughly 35 mpg. Online converters give the same result and are handy for comparing cars.
Why is my real mpg lower than the official figure?
Official figures come from controlled tests. Real driving includes traffic, short trips, cold weather, heavy loads, high speed and under-inflated tyres, which all use more fuel. Tuning, servicing and gentle driving can narrow the gap but rarely close it.
Does CO2 emissions tell me the fuel economy?
For similar vehicles using the same fuel, a lower CO2 figure normally means lower fuel use. It is only a rough guide across petrol and diesel because the fuels contain different amounts of carbon. Check the official fuel figure where you can.
Do electric cars have an MPG?
Not in the usual sense. Electric vehicle efficiency is shown in miles per kWh, and some sources quote MPGe to compare with petrol. Range depends on battery size, temperature and driving style. Tax treatment of electric vehicles can change, so confirm it on GOV.UK.
Official Sources
Rules, fees and deadlines change. Confirm anything that affects your money or legal position with the official service.