Unfortunately, you can't totally ignore this tattered excuse for a set-up because the plot doesn't just revolve around the predictable rebellion-of-the-oppressed-lower-caste led by Chris Evans as Curtis. In order to get through the security systems locking one car from another Curtis recruits a drug-addled former security-system designer, Namgoong Minsu. With his hop-headed and possibly psychic ?girlfriend? Yona, Minsu has his own reasons for helping Curtis make it to the front of the train where he will face the sudden yet inevitable betrayal of... oh, please, don't tell me you didn't see THAT coming a million miles away.
Look, it's not just that the premise is terrible (it is) and the plot is hackneyed (it is). It's that I Just Don't Care. Once upon a long ago I read Nevil Shute's On The Beach, a novel about survivors of a world-ending nuclear war in a submarine trying to reach Australia. About 2/3 of the way through the book I realized that I had run out of damns to give because even if they did make it to Australia they were all going to die anyway, in short and gruesome order. Same thing with Snowpiercer. Even if I give them all the credit and ignore all the wrong, they're still dead. Dead dead dead. So everything they do is meaningless - and I don't invoke the bizarre meaninglessness of, say, Waiting for Godot. I mean, like, meaningless because there is no future and so no present action can have any lasting effect. Therefore, I do not care. They could all die, or all kill each other in the next scene in yet another axe-swinging gore-fest or some cute child might somehow miraculously live. It's all the same in the end.
As a footnote, I will say that Tilda Swinton does a remarkable job of playing a clearly unhinged sadist fanatic.