Electrical system failures take the second spot on the list because they're the second most common cause of car fires [source: Walters Forensic Engineering]. Car batteries are problematic, and not just the hybrid and all-electric vehicle battery pack types we've already discussed. A typical car's standard battery is capable of causing plenty of trouble. The battery's charging cycles can cause explosive hydrogen gas to build up in the engine bay, and the electrical current the battery provides (along with faulty or loose wiring) can produce sparks that can quickly ignite a fluid drip or leaked vapors. The electrical system's hazards aren't confined to the area under the hood, either. Electrical wiring runs throughout the entire car; through channels, into doors, under the carpet and through powered and heated seats, just to name a few places where a stray, unnoticed frayed wire could cause havoc.