Like others have said, it would depend on the particular car seat you have. And it also depends on how tall you are/how far you have the seat back.
I had a Peg Perego rear-facing in the middle without any incidents, and I occasionally run the Britax Marathon forward facing in the middle as well - legs dangle just fine, but when they're feisty they can reach your headrest pretty easily (also depends on how big the kid is).
Two passengers would be a stretch - they'd probably want to be pretty darn skinny as the middle is not that wide to begin with so the car seat will likely overlap with part of the two passenger seats. If you wanted to carry just one passenger, I'd advise to move the car seat over to the right (I know that middle is a "must" for you, but perhaps this can be considered if you are in a pinch) and let the passenger sit behind the driver.
Note: Keep in mind this is for my '05 - I don't have any firsthand experience w/ the second-generation TSX so I can't comment much about that.
I had a Peg Perego rear-facing in the middle without any incidents, and I occasionally run the Britax Marathon forward facing in the middle as well - legs dangle just fine, but when they're feisty they can reach your headrest pretty easily (also depends on how big the kid is).
Two passengers would be a stretch - they'd probably want to be pretty darn skinny as the middle is not that wide to begin with so the car seat will likely overlap with part of the two passenger seats. If you wanted to carry just one passenger, I'd advise to move the car seat over to the right (I know that middle is a "must" for you, but perhaps this can be considered if you are in a pinch) and let the passenger sit behind the driver.
Note: Keep in mind this is for my '05 - I don't have any firsthand experience w/ the second-generation TSX so I can't comment much about that.
