A few days ago a story made the rounds on the Internet (as they usually do) that raised a few eyebrows regarding the Chevy Volt. GM’s much-ballyhooed plug-in hybrid, which can go 40 miles on electricity only, would apparently require premium gasoline to power its battery generator. Premium fuel carries a premium price, usually 20-30 cents more per gallon. So much for saving money on gas.

Turns out that yes, the Volt is calibrated to run on premium fuel, for reasons I will get into below. However, it is equipped with a knock sensor… which means the engine can “detune” itself to run on regular fuel.