Question about vehicles path/behaviour/speed

[Wiki 1558]

Hi there.

 

Got a few questions:

 

- how come 2 vehicles, not grouped, following each other with the same settings don't have the same speed? it often happens that the following vehicles bumps into the first one.

- how come 2 vehicles, not grouped, with both "hold" waypoint don't start at the same time when the "hold" WP is off?

 

Thanks