Thats a fair perspective, however the duration of the shock isnt important, the shock itself is. A static electricity shock such as the door knob shock you mention is by far capable of doing serious damage to any intergrated circuits in the car.

Even though older cars are pretty safe to get away with that practice, it still should be avoided. A GM with an internal regulator is subject to damage from that effect by itself, not to mention if there was an aftermarket radio/cd player in the car. Dont forget aftermarket guages as well.

If anyone wants to try this practice with an AutoMeter tachometer, disconnect your battery with the car running and rev it up a few times, reconnect the battery with it running and see how well that tach works.

Its a practice that should have disappeared before leaded/regular gas.