Every 12 volt coffee maker has a 12V DC plug that goes into what was once described as the cigarette lighter socket on the dash of your car, RV or boat.
Other than the plug, there are a lot of differences between the various types of 12-volt coffee maker you can buy.
Some are suited for RVs or boats with a family of coffee drinkers on board. Others are designed for lone road warriors who want to be able to brew of quick cup of coffee at any time.
For RV and boat use you can also use a drip brewer that plugs into a dashboard of some kind.
But there are other ways to make coffee while you travel.
(And yes, there are kettles designed to plug into a 12-volt outlet, like the Max Burton Coffee to Go.)
The Aeropress is particularly well suited to travel because it is made from a high impact plastic is pretty much indestructible.
While the 12-volt plugin brewer is still a favorite among RV users, there is a growing interest is different kinds of coffee makers for anyone "on the go". This interest is probably fueled by the very poor quality of coffee brewer found in most hotel rooms.
Hence the growing interest in the Aeropress and press pots that are tough enough to travel, like the Espro.
If you need a brewer that plugs into a vehicle, go for the 12-volt option. If you simply want a brewer that will travel, there are plenty of other options to explore.