Question. Context: VINs were first used in 1954. From 1954 to 1981, there was no accepted standard for these numbers, so different manufacturers used different formats.

Question: when did they start putting vin numbers on cars?
Answer. 1954
What step-by-step reasoning justifies that answer?
Reasoning: The relevant information to answer the above question is: VINs were first used in 1954.