A fancy-sounding yet affectionate name for a car that is even less functional than a hoopty. A car might be called this because "it rolls down one hill, and canardly get up the next".
Exact origin unknown, but it is a pun on Rolls Royce, a particularexpensive make of motor vehicle, and "Canardly", I believe a make of small passenger aircraft.
The thankless task of being the first one to take a hit, from the practice of coal miners of bringing down a caged canary to see if there's dangerous gas below