Pretty much any party that has less than 6 people is going to have "hitchhikers." But, as PP said, it's much less intrusive there than somewhere like Biergarten. The cars have three rows, all facing forward toward the screen in the front, and each row seats two. So, while you might see the backs of the heads of the people in front of you, you're not interacting with them at all. We usually just travel with two of us, so we're typically in the front, with people behind us (in which case you don't see anyone else at all), or we're in the very back with two rows ahead of us, but that has never bothered us either.
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