Hello Macca,

Do not worry – you are not alone in being confused! Ever since BMW launched the first-generation 5 Series in 1972, creating the 5xxi template of badging for its cars, it has varied between either clearly stating the engine capacity on the boot (i.e. a 2.8-litre 3 Series from the 1990s with a 328i badge) or using neater numbers to round up or down – the 4.4-litre V8 5 Series of the mid-2000s, for example, was badged 545i, not 544i. Currently, BMW uses modular engines with 500cc cylinders, meaning a three-cylinder engine is 1.5 litres, a four-cylinder engine is 2.0 litres and a six-cylinder engine is 3.0 litres. The boot badging then determines different power levels of the same engine, and so you get more discrepancies between the badge and the actual engine capacity: for instance, in the 3 Series family, at the moment the 320i and 330i both use the same basic 2.0-litre, four-cylinder petrol unit, but the former has 184hp/270Nm, while the latter has 252hp/350Nm. It’s essentially all very confusing and leads to the situation you describe – both 318s and 320s advertised with 2.0-litre engines!