It occurs to me that when WBUR started producing Car Talk, there may not even have been an NPR hourly newscast available for the hours when Car Talk would have been running. The full 24/7 slate of hourlies didn't start until after 9/11, as I recall.
In any event, it certainly would have been possible for a station like WFDD to have run the Car Talk segments delayed by a few minutes to play the network news, especially if you then pull out the two 60-second blocks of filler music at :19 and :39. The show would then end a little past the top of the hour, but if whatever's next is local and not another timed-to-the-hour national show, so what if you're ending at :01 or :02?
You might be right, but like I said I never listened to my local station too much if ever at the start of Car Talk to even have noticed if they had run a newscast, and just how did Car Talk get on the subject anyways, as I start the topic on Wait Wait Don't Tell Me, and Car Talk has been over the air for new episodes since October of 2012, and I don't know how many (if any) NPR member stations that air Car Talk repeats.