For some unknown reason, yellow sac spiders are drawn to building webs in the evaporative canister vent line of the Mazda6 sedan. It sounds bizarre, but it's true -- and it's enough of a problem that Mazda has recalled about 52,000 of the cars to inspect and, if necessary, repair damaged fuel systems.
It's unclear why the spider is drawn to the 2009 and 2010 model-year Mazda6 or why, in all 20 reported cases of spider infestation, the car in question had a 4-cylinder engine rather than the optional V6 powerplant. But when infestations do happen, the web buildup can block the evaporative canister vent line -- the path that air leaving the gas tank travels through and is cleaned by a charcoal-filled cylinder -- which can lead to a cracked gas tank and possibly a fire. No fires have been reported.