YOU SAID:

we are in a car going somewhere

INTO JAPANESE

私たちは車に乗ってどこかへ行っています

BACK INTO ENGLISH

we are going somewhere in the car

INTO JAPANESE

私たちは車でどこかに行くつもりです

BACK INTO ENGLISH

we are going somewhere by car

INTO JAPANESE

私たちは車でどこかに行く予定です

BACK INTO ENGLISH

we are going somewhere by car