YOU SAID:

car hit him right in the back of the upper leg

INTO JAPANESE

車は彼の右脚の後ろで彼を襲った

BACK INTO ENGLISH

The car hit him behind his right leg

INTO JAPANESE

車は彼を右足の後ろにぶつけた

BACK INTO ENGLISH

The car hit him behind the right foot

INTO JAPANESE

車は彼を右足の後ろにぶつけた

BACK INTO ENGLISH

The car hit him behind the right foot