A tattoo is a deeply personal act of bodily adornment; asking why a person chooses something is not always a reasonable question. Still, and despite our rabid love for "Captain Slow," we cannot understand why someone would want a portrait of Top Gear's James May on his thigh for the rest of his life.
Not to disparage the idea of showing deep enthusiasm through inky needlework, but there is no shortage of other people or car motifs that make more...I mean, really, dude: James May? Captain Slow? Motivation is a mystery, humanity is a wonder.
(Hat tip to MrQuick!)