What was used to measure engine size before litres (or CCs) and when did metrication happen?
Metric was used in Europe from before cars, so European manufacturers have always used litres or ccs. The British originally used a form of horsepower – but it was calculated rather than measured, so was not a reliable indicator of the output of the engine. However it was used for taxation, and gave rise to model names such as the Austin 7 and Standard 10. France used something similar (and still does for taxation) hence the Citroën 2cv. Litres (and cc) became common from the late 50s (e.g Morris Minor 1000). American manufacturers used cubic inches until the late 70s or early 80s.
