The TL and TSX would be a good car to begin with. I would definitely stay away from VW at all costs; terrible reliability and high repair bills. I would suggest he gets something he is able to work on if it were to ever fail. This could ultimately save both him and your parents money in the long run.
Just because he's managed to save up $6k doesn't mean he should spend it all on the car. He should take into account insurance, gas, unexpected repairs, etc. Have you, him or your parent's looked to see what insurace would be for any of the cars he's interested in? That could be a deciding factor as well.
I thought your first car was an LS400?
Peachtree City seems to give this effect that anything shy of a European luxury car is not good enough. I'm not saying your brother has this mentality but look at how the rest of the kids are. They're used to getting H2's, E46 & E90/92 3-series, E39's etc.
Please don't take my posts as being a dick or anything, I'm just trying to play devils advocate. I'd hate to see your brother get into a car that's way over his ability to fix if it were to break. Trust me, I was the same way when it time for me to get my first car so I know what he's going through.