Question: how big is my cars engine

Without knowing the make and model of the car, we can’t tell, but perhaps we can put some limits on it and make a best guess using the information we do have access to. It can be a useful exercise in how we look to solve problems and answer questions – work out what’s being asked, set practical limits and work out a best first guess based on the data availble. The answer will almost certainly be wrong, but we can use that wrongness to improve and ask more or better questions
Let’s have to look at your question “How big is my cars engine?” – there are three terms here to give meaning to – “big”, “car” and “engine”.
We’ll start with engine, it will make things easier later. We think of engines as machines that convert chemical energy or heat into motion. Motors convert electrical energy into motion. So for this lets rule out electric motors and stick to internal combustion engines.
Next “car”. We’ll rule out push cars and pedal cars in which you are the engine. We’ll rule out other vehicles like ships, lorries, construction and quarrying equipment. We’ll rule out cars you can’t easily buy like rocket or jet powered cars, drag cars, F1, or extreme modifications. We’ll rule out micro cars, bubble cars, quadricycles and classic cars and stick to only those an ordinary person can buy (apologies if you’re not an ordinary person, it’s just to make the example simpler). The legal category is a “Domestic Passenger Vehicle”. We’ll use that
Next “big”. There’s many ways to describe engine size – the physical size, the cylinder volume, the power output. Cylinder volume and power output are easiest to get data for, so we’ll go with those.
What information do we have? Well, there’s not much in your question, but we do have published records from car makers and car registration statistics, so we’ll use those.
Industry figures suggest the smallest engines sold into the UK market are around 1litre total cyclinder displacement (or very slightly lower) and the largest are around 3 litres, although volumes up to 6.75 litres are possible if you’re lucky enough to be buying at the very far luxury end of the market. Diesel engines are typically larger than petrol ones.
European figures are easier to come by than British ones, and they suggest that, for 2024, the average engine size was 1.554 litres and 115kw power output. Petrol cars averaged slightly lower at around 1.5 litres and diesel cars slightly larger at around 1.86 litres. It varied between countries as well, northern coutries tending to be a bit larger than southern one. The UK isn’t listed, but Ireland is, so we’ll assume we’re like Ireland. The average engine there was 1.595 litres displacement and 107kw in 2024.
So, whilst we can’t know what the size of the engine in your car is, assuming your car is a classed as a domestic passenger vehicle and that you’re in the UK we can take a reasonable guess that the size of your car’s engine will be between, say 980cc and 3litres, with 1.6 litres and 107kw being a good first guess. It will be wrong, but hopefully not too wrong.