After a month of watching Merlin drive, fiddling with the buttons on the dashboard, and getting used to traveling in a car, Arthur is given a chance to drive when he bothers Merlin enough. Arthur even documents the trip along with all of his other ‘firsts’ of the modern world.
[Of course this is only after hours of going over the rules of the road and telling Arthur it wasn’t okay to drive through the intersection on a red light even though no one was around - 'But Merlin, what's the point of these flashy things if they don't even work right?' - or to honk at other drivers when they annoy him - 'Where's your blinker you idiot?' - or to not wear his seat belt - 'This is ridiculous, Merlin, I'm not going to crash. I'm a perfect driver' 'How do you know? You've never driven before!']