Overnight storms in Knoxville, Tennessee, sent muddy floodwater coursing down a city street, nearly swallowing parked cars and prompting neighbors to fear the vehicles could not be saved. For households, scenes like these are more than dramatic weather footage. A flooded car can mean lost transportation, missed work, insurance headaches, and a major blow to the family budget. What happened? Knoxville-based reporter Erin Rogers of WVLT News share…