YOU SAID:

The car was going fast

INTO JAPANESE

車が速いつもりだった

BACK INTO ENGLISH

It was going fast car

INTO JAPANESE

それは高速車を行っていた

BACK INTO ENGLISH

It was going fast cars

INTO JAPANESE

速い車です。

BACK INTO ENGLISH

This is a fast car.

INTO JAPANESE

これは高速車です。

BACK INTO ENGLISH

This is a high-performance car.

INTO JAPANESE

これは高性能車です。

BACK INTO ENGLISH

This is a high-performance car.