From Redditor u/herowcatsmanzzz:
For those of you who don't remember: in season five, a few episodes earlier, Lily and Marshall agree to have kids when the universe sends them a sign by showing them the fifth doppelganger (Barney). They think that they do because they see a cab driver identical to Barney but with brown hair. It turns out, however, that it actually is just Barney pretending to be a cab driver to sleep from women around the world.
The plothole, however, is that Barney has no idea how to drive. They have established this many times because not only did he grow up in New York City, thus having no big need to learn, he obviously has a huge fear of driving (shown in the episode where Ted tries to help him and Barney pees himself because they were driving below five miles per hour and the car bumped a bush).
What I am saying is that Barney never says that he is going to learn again. Even if he did just for this crappy pick up scheme he wouldn't get over his insane fear so easily. In the episode he drives like it's no big deal and like he has been doing it for years.
Just a thought.