[Llarry]

I've not addressed the pre-250 cars as they were not really "production" cars in the modern sense, but Lady Jane's posting reminds me that I should explain the system used for the V-12 cars from the beginning.

The very first Ferraris were two 125S racers with 1.5 liter V-12s. (See the attached photo). The new company soon came up with larger engines and more power.

The numerical portion of the designation was the displacement in cubic centimeters of one cylinder (X 12 = engine displacement), so:

125 = 1.5 liters
166 = 2 liters
195 = 2.3 liters
212 = 2.5 liters
225 = 2.7 liters
250 = 3 liters
275 = 3.3 liters
330 = 4 liters
365 = 4.4 liters
375 = 4.5 liters
375 Plus = 4.9 liters (a little cheating going on here...)
412 = 4.9 liters
456 = 5.5 liters

I may have missed one or two numbers in that list; Ferrari was doing a lot of experimentation with different powerplants in the early days and engines were swapped back and forth a bit as well. I believe the 1990s Ferrari 456 was where the above system stopped being used and note that the V-8 cars used a different system.