I do this on pretty much every forum I am on. Can't see anything tho on my iPhone as it displays the page in a different format.
I think there are two sides to listing your cars.
1: showing off what you have worked hard for
2: people perceive you as an arrogant prick that has too much money.
For reasons above, I list my cars on the higher end forums but on the cheapy ricer, children infested boards, I keep my signature blank. I'm fairly young still, only 29, so for my age, I get a LoT of shit for owning the cars I do. Comes with the territory I guess.