The Sierra Club still thinks car exhaust is dirty, but here's proof that automakers aren't lying about cleaning up emissions: It's mighty tough to kill yourself with car exhaust nowadays. In one medical journal report, a 56-year-old man tried to commit suicide by running a hose from his exhaust pipe into the inside of his car. Rescued and rushed to the hospital, the man was still conscious after breathing fumes for an estimated “eight to 10 hours.” Tests revealed the level of carbon monoxide in his blood was less than half the lethal level. According to recently released figures, the number of suicides by carbon monoxide poisoning has dropped dramatically since the mid-1980s, while the overall suicide rate has declined only slightly.