Japanese cars like the Datsun they compared it with would have no problem whatsoever. Even some German cars like a Mercedes or a BMW would have had no problem at all. It's all a question of quality.
Also, Season 11 Episode 1 = win.
But the car becoming a swimming pool is not a question of quality because under no circumstances was a car designed with that in mind. You'll always get leaks around the door handles, where the door seals aren't touching just so and the various openings in the firewall and whatnot. It's just not a test of quality in any way. The producers just wanted to make it sensational and really had no care if they discovered car quality or not.