Bill Boddy at racing speeds though, relative to each other they will seem almost stationary. That's what allowed this sort of thing at speeds of 200mph or so without them touching:

20.4 Any driver defending his position on a straight, and before any braking area, may use the full width of the track during his first move, provided no significant portion of the car attempting to pass is alongside his. Whilst defending in this way the driver may not leave the track without justifiable reason.
For the avoidance of doubt, if any part of the front wing of the car attempting to pass is alongside the rear wheel of the car in front this will be deemed to be a 'significant portion'.
"clumsy"