Rav Wosner says mentions in a psak that Driving is like “????? ?????” which is asur.
As we find by Rivka emainu that she was a tzanua when traveling with Eliezer…
Although there might be nothing unmodest about driving a car, a vehicle is definitely a man’s domain. (the same way a moped, scooter, bike, etc. is)
Bottom line, tzniyus is required at all times and even when riding a car as a passenger (getting in and out…)
It boils down to Kol kevuda bas melech penimah!
There’s a time and place for everything!