well first off hope no one got hurt in the wreck!
I just got my first BMW, and its a 2007 335i, HTC, with 42,000 miles, before I purchased the car I had the dealer actuate the top with me standing in the back listening to the unit so in case there were issues of noise I would hear them. so far the top has worked perfect. no leaks but then I was the car in the drive way and blow dry it with the leaf blower. I read thru Kats thread on top maintenance, purchased the rubber care products, and the HHK grease she recommended. I have lubed everything on the top, and greased the seals every saturday so far. It appears the previous owner neglected the seals, but they still look fine. the tension cords are frayed but will get replaced this monday, the only issue I had was the radio head unit was replaced and the car was not reprogramed so the Aux and SAT,USB didnt exist on the radio. However Carmax made good on their claim that within the first 30 days they will fix anything, so to the dealer last friday, they reprogramed the radio, fixed any codes stored in the cars memory and Carmax paid the bill, now everything is back to OEM specs. Now maybe Carmax will pay for the tension cords, not that I expect that, but if they do I will be a Happy, first time,(used) BMW owner! But just check the car out that you plan to buy, get one from carmax if possible, that was one of the best interactions I have every had purchasing a car, from a car dealer.