Several years ago, I had to have the ABS Computer, Carpeting and Wires replaced in my 2008 Smart Fortwo. I was lucky that my insurance company covered it under my comprehensive coverage. There have been hundreds of complaints to my knowledge to Smart/Mercedes. Water gets into the battery box, filling it up. It then flows into the Computer and Electronic bays in the floor of the car. Smart knew of this problem and corrected it in the latter half of the 2009 model year. The AC system plugs up easily with debris, and/or the battery rubs against the drain line. Both problems needed to be addressed and in a timely manner. Once water contamination occurs, it will disable or cause the anti skid system to fail, along with other electronic controls too. Some dealerships charge over $5,000-$6,000 for the repair parts and labor.

Update from Jul 25, 2015: Last April, I discovered that the AC water is again draining into the battery bay and soaking the carpets. So for now, I cannot use the AC system. I am hoping that it has not damaged the Electronics. Smart needs to fix these cars! It is a safety issue!