Yeh I think you're right. It was on here somewhere, or the USA section anyway. Saving money I guess? Won't sound as good though (unless it's added later)
It's fairly common practice for film and TV to use the cheapest cars available and to prep the exterior to look like something nicer. Since actual speed isn't really needed for the camera some of your favourite ever movie chase scenes usually involve pretty lacklustre cars underneath the paintwork and badges sadly.
One of my favourite examples is the original "Gone in Sixty Seconds". As the film was meant to have been shot in '71 they bought several '71 mustang "Eleanor's" brand new, but when filming got delayed by 2 years they just changed the outer trim to look like '73 mustangs. That's a timid but amusing example.
It's rare to have film cars with anything other than the base engine, and even after the rough treatment of filming they often get dumped in a studio lot to rot for years after