What error in reasoning is exemplified by the following statement? my volkswagen constantly needs repairs, and so does my roommate's toyota. we can see, then, that foreign cars are unreliable.

Well, it does not take into consideration what kind of repairs it needs. Maybe they accidentally run over potholes or have hit a curb to knock the alignment off. or maybe a rock chip. those are not the manufacturers fault. they also have not tested non foreign car brands since the only two cars involved happen to be foreign... (also it is false because Toyota and Volkswagen are very reliable cars)

Perpendicular line? no.