Not long after the Tesla Model S was awarded the unofficial title of "the safest car ever" by the media (and by Tesla Motors), a Tesla Model S caught fire in the fall of 2013. That's never good, of course, but for Tesla, it was especially bad. The company had implied numerous times that its fully electric Model S was all but immune to the battery-related problems that have plagued hybrid cars and EVs of the past. Alas, a Model S traveling at high speeds hit a piece of debris that punctured the car's battery, and the battery behaved like any other battery would: it ignited.
Throughout 2011 and 2012, the Chevy Volt made headlines when a bunch of test vehicles caught fire during impact testing. Federal regulators determined that in most of these cases, leaking coolant interacted with the damaged batteries to spark the blaze, and General Motors was able to come up with a fix that satisfied government safety officials. Concerns about hybrid and electric batteries go way back, though, and there are new potential risks with each new design. It might be a while before the safety concerns from these high profile incidents fade from the public consciousness.