YOU SAID:

I saw a car with a license plate that said "NYOOM" on it nyoom by.

INTO JAPANESE

私はナンオムで「NYOOM」と言ったナンバープレート付きの車を見た。

BACK INTO ENGLISH

I saw a car with a license plate that said "NYOOM" with Nan Oum.

INTO JAPANESE

私はNan Oumと "NYOOM"と言ったナンバープレート付きの車を見た。