I've been curious about the material of which these lines are made, since I got my 240D. I don't think it's plastic as that wouldn't hold up to the temperature extremes and harsh under hood environment, in general. Extreme heat or cold and everything in between and they don't lose their grip, shape, texture, etc. I'm guessing/speculating possibly nylon or maybe even teflon? Does anyone know for sure? Whatever it is, it's very strong and quite stable through all operating parameters and age.