。
An icy chill crept into the car.
Literal
Ice [like-のような] cold-air [subject-が] inside-car [to-に] crept-in.
氷のような冷気 uses のような for 'cold air like ice.' 忍び込んできた combines 忍び込む ('to sneak in') with てくる ('coming toward the speaker'). A descriptive, atmospheric sentence.