Three different questions hide behind this one. How big is the engine, which the record answers exactly. What does it run on, which the record also answers. And which engine is it, meaning the manufacturer's code for the specific unit, which decides parts, oil, service intervals and whether a known fault applies to you. Only the first two come from the registration.
What litre is my car? Capacity, fuel and the engine number
The DVLA vehicle enquiry and the V5C both carry the cylinder capacity in cubic centimetres, the fuel type, and the engine number stamped on the unit. Capacity in cubic centimetres converts to the litre figure everybody uses by dividing by a thousand and rounding, which is why a car sold as a two litre reads as a number slightly above or below two thousand. The fuel field distinguishes petrol, diesel, hybrid and electric, and it is the field that answers the cheapest version of this question.
What engine does my car have? Why the engine code matters most
Manufacturers build several engines of the same nominal capacity, and they differ in fuel system, turbocharging, timing drive and known weaknesses. The code identifies which one you have, it is usually stamped on the block and recorded in the build data against the VIN, and it is the thing a parts supplier, an independent specialist or a recall notice actually works from. Ordering parts by capacity alone is how people end up with the wrong timing kit.
Reading the fuel economy figure
Published consumption is a type approval number produced in the same laboratory testing that produced the emissions figure, expressed per model and derivative rather than per car. It is a comparison tool between vehicles tested the same way and not a prediction of what you will see. Real consumption depends on the route, the load, the weather and the driver, and a car whose real figure is a long way below the published one is usually reporting the driving rather than a fault.
When the engine is not the original one
An engine swap is legitimate and has to be notified to DVLA, which updates the engine number on the record. So a record whose engine number does not match the unit in the car means either an unnotified change or something worse. Check the capacity and the fuel type against the badge and against the physical engine, and on a car with an unusual history read the engine number off the block rather than believing the document.
Questions people ask about what engine is in my car
What engine size is my car, and can the registration tell me?
Yes. The free DVLA enquiry returns cylinder capacity in cubic centimetres and the fuel type, and both are printed on the V5C as well.
Does the record show the engine code?
No. It carries the engine number, which identifies the individual unit, not the manufacturer's code for the engine family. The code comes from the block and the build data against the VIN.
Is my car petrol or diesel, and can the plate tell me?
The DVLA enquiry has a fuel type field, so the registration answers it. On the car, the filler cap label and the engine bay are the physical confirmation.
Why does my car use more fuel than the published figure?
Because the published figure is a laboratory result for the model, produced under defined conditions. It is a comparison between vehicles, not a forecast of your own driving.