[BE911SC]

It means that the person choosing to use the term sees a modified car as having been mistreated by someone against its will. It is, to me, a derogatory term with a sarcastic element meant to show disdain for a modified car.

mo·lest
məˈlest/Submit
verb
1.
assault or abuse (a person, especially a woman or child) sexually.
"he was charged with molesting and taking obscene photographs of a ten-year-old boy"
synonyms: (sexually) abuse, (sexually) assault, interfere with, rape, violate; More
2.
dated
pester or harass (someone), typically in an aggressive or persistent manner.
"the crowd was shouting abuse and molesting the two police officers"
synonyms: harass, harry, hassle, pester, bother, annoy, beset, persecute, torment; informalroust
"the crowd molested the police"

It goes along with the sexual terms "virgin" and "cherry." It's still a virgin and hasn't lost its "cherry." Thus, it is more valuable.

What do we want? The virgin original. The one not molested by the hands of some careless brute. Why? Because we want to be the first one who gets to do that.

I'm talking about cars. (Get your mind out of the gutter!)