West Midlands Police said that while patrolling around Handsworth, the Roads Policing Unit officers spotted a grey Nissan Juke with cloned plates and, after using tactics to bring it to a stop following a short pursuit, all four were detained.
Following searches by the officers, the car was found to be stolen in July, while further searches from the officers found a live bullet, Class B drugs and cash.
All four were arrested on suspicion of theft of a motor vehicle.
One of the four, a 17-year-old boy, was also arrested for possession of ammunition and Class B drugs.
Another of the four, a 19-year-old man, was also arrested on suspicion of failing to stop and driving without insurance.
The force confirmed that all four remain in custody for questioning.