Few words about BMW 5 series:
The 5 series got its name by being the fifth of the "New Series" BMW cars, preceding by BMW 700, "New Class", "New Six" (BMW 2500, BMW 2800, BMW Bavaria) and BMW CS. The body of E12 model, first generation of 5 series, was styled by Marcello Gandini from Carrozzeria Bertone, and was inspired by BMW Garmisch 2002ti prototype, showed in 1970 Geneva autoshow.
The 5 Series began the BMW tradition of being named with a three-digit number (BMW 520, BMW 540i etc.). The first digit represents the model number (5), and the other represents the size of the engine (thus, BMW 520 means BMW 5 series with 2.0 liter engine). Additional letters represents fuel type or engine details, for example 'i' stands for 'fuel injection' and 'd' stands for 'diesel'.