Since a majority of Americans already drive around with a tank full of volatile and flammable gasoline, one would think people wouldn’t worry about exploding natural gas vehicles. Apparently GM thinks there’s enough concern that they decided to shoot the fuel tank on the Chevy Impala CNG with armor-piercing bullets and shove it into a bonfire just to prove how tough it really is.
Now obviously GM is merely adhering to the Federal standards regulating CNG fuel tanks, which call for enormously strong cylinders capable of withstanding some pretty extreme punishments. The cost of these high-strength tanks is one of the main reasons CNG conversions can add thousands of dollars on top of the MSRP of a conventional vehicle. That said, it’s still fairly impressive what they can withstand.
The “Bonfire” test exposes the CNG tank to temperatures of 800-degrees Fahrenheit from every side but up in order to prove the tank won’t rupture in case of fire. Special relief valves are designed to bleed the CNG off as the tank heats up, which adds fuel to the fire but prevents a massive explosion like the one seen in this video. GM also put the Impala CNG through various side and rear impact tests to prove it could handle some pretty serious fender benders and not go boom.
Then there’s the “penetration” test, which saw GM put a 7.62 mm armor-piercing bullet shot through the CNG tank without going through the other side. Again this test was done to ensure the tank wouldn’t rapture in an explosive fashion should the structural integrity be comprised by some kind of piercing. At 3,600 PSI there’s a lot of explosive potential packed into these CNG tanks, as well as enough fuel for about 150 miles of driving, after which the 3.6 liter V6 engine switches over to gasoline instead. Toyota performed a similar test with its 10,000 PSI fuel tanks of the Toyota Mirai hydrogen fuel cell vehicle
Of course none of this changes the fact that CNG is at best a sideways solution to America’s oil addiction, and lower gas prices at chipping away at what little advantage low CNG prices offer. Still, I’m all about having more options, and the Chevy Impala CNG is one of the few non-petroleum, non-plug-in cars you can buy today.