YOU SAID:

seventeen people in a a car

INTO JAPANESE

車に乗った17人

BACK INTO ENGLISH

17 people in the car

INTO JAPANESE

車内に17人

BACK INTO ENGLISH

17 people in the car.

INTO JAPANESE

車内には17人。

BACK INTO ENGLISH

There are 17 people in the car.

INTO JAPANESE

車内には17人が乗っています。

BACK INTO ENGLISH

There are 17 people in the car.