I'm a Car
I'm a Car
[The bottom right rear end of a car is shown with a bumper sticker next to the unreadable license plate.] I'm a car and I vote

This comic was released eleven days before the United States midterm elections on Tuesday, November 6, 2018 and even the header text at the top of the xkcd page had changed a few days before by showing a link to vote.org to help US citizens to register and finding their polling places. Randall uses a neutral way to encourage people to use the right to rule their governmental representatives. Before the presidential election, 2016 , however, he chose the Democrats as shown in the comic 1756: I'm With Her (see more here ).
This comic shows a car with a bumper sticker , which is generally a thin rectangle piece of plastic with a message on one side and adhesive on the other side in order to stick to a car.  This allows the owner of the car to display a message they want to present to whoever is driving behind them or in their vicinity.  Bumper stickers are usually used to express a viewpoint, whether personal or political, held by the owner or driver of the car.  This comic makes literal the ones that include or allude to the personal pronoun "I" and its variations, i.e. first person singular statements.  Of course the intent is that "I" is referring to the person who put the bumper sticker on the car, but as the sticker is attached to the car the more literal interpretation is that "I" is referring to the car. So the humor is derived by the notion that the car itself is making these statements.  (On an even more meta level, the comic could be interpreted as saying that the person who wrote the words in the comic, i.e. Randall , is saying that he is a car.)
The bumper sticker on the car in the comic is a variation of a sticker used to both encourage people to vote, as well as express their political position: "I'm a ___, and I vote" (where the blank is traditionally filled in with "Union Worker", "Catholic", "Senior Citizen", "Gun Owner" or some other demographic or organizational membership). However here it is attributed to an automobile which is not capable of voting [ citation needed ] .
The comic could be an indirect reference to the growing "intelligence" of self-driving cars , such that one day they might have the intellect to communicate, vote, and engage in other self-motivated activities. See ‘ Sally ’ by Isaac Asimov . It may also relate to security concerns around increasing use of electronic voting mechanisms - the joke being that the car is able to abuse the interfaces to such systems either to vote on behalf of its owner or as its own entity. Though voting might not be one's biggest concern if their "intelligent" car got dragged into a bot net...
The title text seems to be another typical message on a bumper sticker, saying that the driver is a "Proud Parent Of An Honor Student". However, this sticker is a bit longer, since it continues to state that "the person driving me is proud, too". Thus once again it is the car who is the proud parent. And thus maybe it is a car that is the honor student?  Another thought is that this may be a reference to the 1965-66 TV sitcom My Mother The Car .
[The bottom right rear end of a car is shown with a bumper sticker next to the unreadable license plate.] I'm a car and I vote
