In the 1964 version, the lightning with a ring was used in a yellow rectangle, with the Opel writing below. The whole logo was again delimited by a black rectangle. The basic form and proportions of the Blitz logo has remained unchanged since the 1970 version, which made the lightning tails shorter so that the logo could fit proportionately within a yellow square, meaning it could be displayed next to the 'blue square' General Motors logo. In the mid 1970s, the Vauxhall "Griffin" logo was, in turn, resized and displayed within a corresponding red square, so that all three logos could be displayed together, thus signifying the unified GM Europe.
It had some crazy mechanical issues. At one point it stumbled and stalled because the carburetor had come loose from the intake manifold and I had to tighten it back down! Another time, my brother was driving it and the brakes failed. Somehow the end of the brake shoe that meets the brake cylinder piston had become worn on one side, causing the piston to slip off the end of the shoe when the brakes were applied, losing braking and squirting fluid all over.