TZNIUS_ means modesty- which means not being flashy or sticking out. Like what noitallmr said don’t think there’s any problem in woman driving in all issues including Tznius. But it depends what car though. If it’s a flashy colored car or 4 x 4 I think that’s wrong but a normal 5/7 seater car’s fine.
modesty MEANS NOT STICKING OUT. FINISHED.
THERE is a gemarah in meseches avodah zarah daf 18a relates the story of rav chanina ben tradion (one of the asarah harugei malchus HYD) and what happened to his entire family about his daughter the gemarah says ??? ??? ???? ????? ?? ????? ???? ?’ ????? ??? ??? ???? ??? ????? ???? ????? ???? ???? ??? ???? ???????? ?? ???? ?? ??? ????? ????????? Trans. She was put in the bais Znus and the midah c`neged middah is once she was going in front of some officers of rome. she heard one of them commenting HOW nice is her steps [ the way she walks]
after hearing that she was careful about her steps [ lit. she walked even nicer] and it is middah k`neged middah etc.
REb mattisyahu solomon shlita in amussar shiur translated and learned the gemarah like this
SHE WAS EXTRA TZNIUS TO THE POINT WHERE SHE STUCK OUT. SHE THOUGHT BY DOING THIS IT IS TZNIUS BUT THE POINT OF TZNIUS IS NOT TO STICK OUT. AND WHEN SHE HEARD THE OFFICERS SHE WALKED REGULAR. TZNIUS IS TO BE NORMAL AND NOT FLASHY. THAT IS WHY IT IS ASSUR TO WHERE RED.
ALSO SHMIRAS AYNIAIM IS A CHIYUV ON THE MAN NOT THE WOMEN
POSEK HADOR