Re: Perfect and perfective aspects in passive voice in German and English
Regardless of the various analyses in subsequent posts, I can't help feeling that the passage quote in the OP contains a misplaced adjectival participle. It should be "stolen car", not "car stolen".
In that case, it can just as easily be "The stolen car is mine" or "The stolen car was mine", because "stolen" could refer to a theft either in the past or in the present. However, if the speaker was talking of previous ownership, then he/she would say "The Stolen car had been mine".
Amo ergo Sum. My words speak for themselves. Between the lines you will find nothing but blank spaces.