Feel bad for the father..

Trevor dad?
Why was he mentally challenged?
To me he was just an ordinary person that could not cope with a sick son. That happens all the time in the real world.

I can't be bothered to have a sig any-more.

He looked like he had a speech impediment or was slow maybe.

I can't say I feel bad for Trevor's old man, because he abandoned him after all, and was less than pleased to see him show up at his dealership. He didn't know what to say, and tried to buy some gratitude with the $ in his wallet. Still, I noticed his bizarre speech pattern and it's very weird that it wasn't addressed at all. I'm guessing he doesn't show up in TV or radio spots for his own dealership, lol.

I'm watching now and just saw this scene. I kept trying to figure out what what going on with the dad, if it was some mental slowness, speech impediment, or just bad acting?

I don't get why they changed this part of the story. In my opinion it was the wrong decision. In the book, the father isn't a jerk. He's just this sad sack, milquetoast guy who was young, stupid, and emotionally ill equipped to handle the realities of his son, and he is desperate to make amends. He and Trevor reconcile.

Rewriting Trevor's dad into some cliche deadbeat does not serve the story well. It looked way too heavy handed.

Fred Weller has always sounded like that in everything I've seen him in, which is a slow, stilted speech pattern. He doesn't move his mouth much when he talks, so if he doesn't slow down his words, they would just come out as a mumbled jumble.

I saw it as this guy with a homey "Aw, shucks" accent, but he's doing a lot of mumbling because a room full of strangers (a man, a pregnant woman, and a teenage girl) are all watching him own up to being a horrible father. Notice how hard it is for him to look at them. I think it's his smarmy car salesman personality crumbling under the circumstances.