The 313 is the vehicle of choice of Donald Duck.
The 313 is a funny-looking, little red or red-and-blue car. Perpetually out of date, and prone to breaking down at inconvenient times, it is cherished by Donald Duck all the same. It has been the subject of many customizations; firstly, as the car had only one actual seat, its boot was modified to serve as the threefold children's seat of Huey, Dewey and Louie Duck; secondly and more thoroughly, many gadgets were concealed within the car's chassis by Gyro Gearloose when Donald became the Duck Avenger, although he never makes use of these gadgets when not acting in the name of the Avenger.
Several conflicting accounts exist of where the car came from and how Donald acquired it. According to some accounts, Donald built the 313 by himself by putting a 1920 Mixwell engine into a 1922 Dudge body on 1923 Paclac axles, with the wheels of a lawnmower attached. It’s the only car that he has ever owned. Donald pays extra each year to keep the ‘313’ license number. According to him, his car’s long life hinges on that number.
According to yet another account, Donald acquired the 313 at some point during his high school years after taking out a loan of $5 from his uncle, Scrooge McDuck, in an attempt to impress Daisy Duck and convince her to go to the prom with him. Of course, this source does not specify if Donald used the money to purchase the car itself, or if he simply bought the parts with which he build the car. Thus, this account could still be compatible with the ones that state or imply that he built the car himself.
Behind the scenes
The 313 first appeared in 1937 in Don Donald. The "Mixwell" and "Dudge" car brands are just distortions (for copyright reasons) of the Maxwell and the Dodge ones respectively. Paclac, meanwhile, is a mix of Packard and Cadillac.
Carl Barks occasionally referred to the car as a "1934 Belchfire Runabout", a descriptor which could also be applied to Donald Duck himself. This may, in fact, be the model of the car, if one takes the account in which Donald bought the car as fact, or, going by the account which states that Donald built the car, it may be a name which Don himself bestowed upon the vehicle.