Someone commented before about flashy cars not being tzniyus. I just wanted to add that it works for both men and women. Men (who normally buy the cars) should not waste time and money on flashy cars- even if they are the ones who will drive them!
Driving seems to be a chumrah that some rabanim have instituted. Please explain what makes driving more untzniyus then WALKING or HITCHING RIDES or FALLING OVER MEN ON BUSES WHEN MEN WONT GET UP FOR THE WOMEN.