Если вы хотите получить json, в заголовке нужно передавать "'content-type': 'application/json'"
В POST нужно передавать в качестве параметра "carIds":
import requests
headers = {'content-type': 'application/json'}
data = '{"carIds":["06a638ab-94b0-4bc7-93c4-d7587b024c77","4cbc03a9-3a4a-478b-8dea-71fe75e2b4ec","7d6a26c9-1e57-4f80-8a06-084bbefaa696","c6f9abd0-d20f-4082-a2bc-1b20f945d0b6","084c175e-e04a-4b47-aaeb-51675284ed84","fa3b0d28-a06d-4bac-bee7-7a56ab5fa829","8c8eba93-f1fa-4f01-ab37-c9a7a2a9f52a","d17b1964-e2a8-4544-afc4-df88ae683ce8","32b960f3-7297-4f90-a06b-6ad8bfe47115","df7b4fc7-f5aa-4a21-9b1b-9700981be14b","3ee17ea7-1654-49b4-9935-4851321fb199","3a3862fe-eb2b-4eec-b640-b9581698ce3b","9be428b5-d035-4384-8936-afa0463e69b3","e0f66af8-eaea-4ba0-a0fe-108fd0cb2aeb","6b9f0304-d4f6-423e-97d0-7799f55a4e0c","90e87e68-37ea-401d-96be-ba9d9783bcd7","d902b121-cb46-4e1e-9b28-53f706ae4b8d","34f18e6c-bf90-42c6-9703-69edc8d4b92b","94baba92-a805-4d8f-a330-2571907afc5e","95f51df1-0746-4bf7-947f-9c9baafae68e"]}'
response = requests.post('https://www.auto.de/service/user-actions/api/v1/stats/viewers', headers=headers, data=data)
print(response.text)
Ну перед этим нужно еще получить carIds.
