I'm arguably paranoid about auto safety from my ambulance days, but I absolutely would not use a stainless steel straw while driving. If you had it in your mouth, or anywhere near your face, during a crash, the results could be gruesome.
But I do like drinking ice coffee from a straw while driving, and would like to stop using single-use plastic straws. While poking around on the internet for a non-plastic, non-metal alternative, I came across these silicone straws from Uncommon Goods, which have a neat feature that makes them easy to clean:
Whoever designed these must've been so psyched, the first time they pulled the prototype out of the mold and got the zipper to work.