Please Make It Clear

The following is the definition of a "please make it clear" moment:

Going out with my little brother to grab a bite of lunch today, we got stuck behind a taxicab. Usual taxicab markings, numbers to call, various regional sports paraphernalia, and so forth. But, on the left end of the trunk were two words... "Police Interceptor".

So, is the cab moonlighting as a police interceptor, or is the police interceptor moonlighting as a cab?