Well considering their COTY criteria of Advancement in Design, Engineering Excellence, Efficiency, Safety, Value and Performance of Intended Function... The Volt meets or exceeds expectations in every single one. All things considered, however, Motor Trend is hardly a rag that keeps everything in check when announcing a COTY winner. Remember the Thunderbird? What about the Cirrus? Hell, they even handed it to the Chevrolet Malibu/Classic.
All of that being said, Automobile Magazine gave their COTY award to the Volt as well. I'm guessing that it is a trend that will be carried over through a wide variety of magazines and websites.
BTW: You probably should have jammed this in the Volt thread. Just sayin'.