[blucar]

From my prospective, it is not a good idea to leave a convertible top down for long periods of time.. I always make sure the top is up and secured at the end of the day. especially in cool weather..
We have a 2004 Mercedes CLK 430, it is my wives car, bought it for our 50th anniversary. My wife is not a car person, she will put the top down, then leave the car sitting outside on the driveway all day.. Reputedly it is her car, so I'll "ask" her to not leave the car sitting outside in the sun with the top down. Bird droppings on the interior don't bother her until she has to sit in the car with same on the seats, etc.
Of course my wife knows I won't leave the car sitting out all night, I actually have to prove a point.. Many years ago I left "her" '57 Bird sit out for a week with the top down.. Being bull headed just put more work onto me to clean it up..
My son learned the hard way to not leave the top down on his Porsche. I finally bought him some top dressing that minimized the damage to the top.. he now puts the top down, enjoys the ride and puts the top up...