For the purposes of this discussion I'm gong to ignore the fact that the the owner of the pictured Mazda truck ruined it by putting a bumper sticker on the paint and focus on the more egregious infraction (note: we're also ignoring the dirty windshield the picture was shot through. Drizzle, out of washer fluid, you get the idea).
The bumper sticker in question reads "My other car is a Firefly." Based on the Firefly reference and the poorly rendered illustration of the spaceship Serenity we can surmise this is a reference to the TV series Serenity.
Ah, so what's the problem?
First the owner's other car cannot possibly be a Firefly. Firefly is a class of spaceship, not a freaking car. Kinda a big difference.
Also, and again, Firefly denotes a class of spaceship and is not the name of the ship poorly pictured on the sticker.
A more accurate version of the sticker would read: "My other mode of transportation is a Firefly class spaceship" or "My other mode of transpiration is Serenity." The last one is doubtful though as I imagine Captain Mal would sooner kick you into Serenity's engine then give her up.
This sticker, along with its placement (oops, I said wasn't going to talk about that) is a total fail. If you are going to make a reference to such an icon, get it right.