The Short Version
The evidence does not support the claim’s central timeline or cause. In 2018, the United States investigated or threatened auto tariffs, but Japan-specific automotive tariffs were not imposed then; the relevant measures arrived later, in 2025. Broader 2018 steel and aluminum tariffs are a different policy and do not substantiate the claim that U.S.–Japan automotive trade tariffs raised Japanese-brand vehicle prices starting in 2018.