We had this conversation a few months ago. Since everyone is posting the same stuff they did then, so will I!
They are real people, not actors. GM selected a large number of people and put them into groups to record the commercial. The marketers probably interviewed the people before they created the groups to optimize the groups. Then they went through the script that the narrator (he's and actor) and crew were aware of but the focus groups are not. Once they record a whole heap of focus groups in action, they edit the recording to provide the footage you see.
It's just business. All of the auto companies try to get you to buy their cars one way or another. I recall a Nissan commercial for a sedan where they put fake ground effects on them to make them seem like race cars and then took a load of people on a wild ride around the track. At the end, the ground effects were removed to reveal a stock sedan. I'm sure those people were not actors either. I'm also sure that the ones we saw in the commercial never took a turn faster than 5 MPH. Of course they were impressed by the handling they never knew existed on a stock sedan. If you read reviews of the cars in the commercials, you will find that the reviewers agree in many cases. The Chevy Malibu does have an upscale interior that could be mistaken for an entry level luxury sedan as one example. IMO some people just don't like GM and are looking for another reason to beat on them.