a) Sit so close to the steering wheel that it must be digging into their chests?! I was always taught that you need to be at just short of arm's length from the wheel to be in total control.
b) Place their sat nav slap bang in the middle of the windscreen and directly in their eyeline, thus blocking their view?!
c) Sit in the middle lane of a 3-lane carriageway when there is nothing in the inside lane?! Or worse, sit in the outside lane when there is nothing in the inside 2 lanes?!
a) short legs I guess as others have suggested.
b) I have mine in middle of the windscreen as far down as possible (so its more or less sitting on the dash) it's not blocking my view and means I haven't got the lead stretched over the dashboard.
c) I have no idea but they're a pain in the proverbial.