Actually not. I thought the AI reaction was the same regardless of whether a plane or ground vehicle attacked. I mean, I can't recall the AI ever keep driving when my bombs start dropping close to them, they always seem to stop at that point.
The default AI reaction to being attacked by an air threat is to disperse for a period of something like 500 seconds. This behavior can be disabled in the group's AI options, as can the length of time the unit remains dispersed.
The reaction to ground threats is totally different. They'll just keep plugging along on their set path until they're dead, the enemy is dead, or they've reached their destination. The only exception I can think of is if they're using a weapon that requires the vehicle to remain static (e.g. an ATGM).