MacGruber features Will Forte in a mullet wig and a whole heapin' mess of NA-generation Mazda Miata screen time. It's meant to be funny. It is, but we also think it's kind of cool.
In MacGruber, Forte's antihero tools around in a red first-generation Miata. If you haven't seen the Saturday Night Live sketch that the movie is based upon, here's the gist: MacGyver-like goof attempts to defuse some random bomb or tricky situation, spends time getting sidetracked by personal issues, invariably dies when he cannot focus. He seeks out action, a'la a broke-ass James Bond, in a first-generation Miata.
You can interpret this a number of different ways. A few members of the Jalopnik staff think it's because Hollywood doesn't understand cars, noting that the Miata is cooler than film studios think it is. I've even gotten a few emails from readers saying the same thing; people like to point out that putting a neat car up as a paragon of goofiness is some larger statement about the incompetence of the movie industry as a whole.