Starting with the October 24, 1937, radio show, when Jack proudly announced the purchase of his car, a running joke began that Benny drove an old Maxwell automobile, a brand that went out of business in 1925.
Although some details such as the car's body style and its exact model year varied over the years, what remained constant was that Benny's old car was so worn out that it would barely run, but the miserly Benny insisted he could get a few more miles out of it.
Many of the sound effects for the car's clattering engine came from an actual old motor that the sound-effects shop had salvaged from a Los Angeles junkyard.
When a sound-effects man missed a cue for the automobile engine, Mel Blanc quickly improvised a vocal imitation of a sputtering car engine starting up noisily that was so funny, it became a regular feature of the show.

The ongoing saga of the Maxwell was initially interrupted after just five years, when on the October 18, 1942, broadcast, Jack took his car to a local junkyard and contributed it to the World War II junk salvage drive, receiving $7.50 in war stamps in exchange.
However, much of the radio audience may have remained unaware that the Maxwell was ever gone, because before long Benny was heard traveling around in a decrepit old car again, and by the end of the 1940s, his car was once more specifically identified as a Maxwell.

When  the Jack Benny Program premiered on television in 1950, a 1916 Maxwell Model 25 Tourer became one of the production's standard props.
Benny's Maxwell later became a 1923 Tourer.
Benny often made public appearances in Maxwells.
He drove a Maxwell onto the stage in one of his last television specials.

By 1941, Jack Benny's Maxwell had become such a well-known aspect of popular culture that it was referenced in the Billy Mills song "I'm in Love with the Sound Effects Man" as heard on the June 17, 1941, Fibber McGee and Molly radio show (and later performed on a 1943 recording by Spike Jones).
The automobile was also featured in the 1943 Benny film The Meanest Man in the World.
Benny and his archaic auto were featured in a series of television and print ads for Texaco from the 1950s through the 1970s.
A series of gags was built around the premise that Benny appreciated the value of Sky Chief brand gasoline in keeping his car running smoothly, but was too cheap to buy more than one gallon at a time.
In the classic cartoon "The Mouse that Jack Built", Benny and his wife are driven by Rochester in a sputtering Maxwell car.

Many people believe that Benny appears behind the wheel of his Maxwell in the 1963 film It's a Mad, Mad, Mad, Mad World, but in fact, it was a 1932 Cadillac.
The long shots for the scene were shot months before Benny was cast—with a stunt driver at the wheel—and the role was intended for Stan Laurel (which is why the character wears a derby, which Benny almost never did).
When Laurel ultimately passed on appearing, Jack agreed to play the role.
According to the commentary on the Criterion edition of the film, his close-ups were filmed on a rear-projection stage at the Paramount studio.
Starting with the October 24, 1937, radio show, when Jack proudly announced the purchase of his car, a running joke began that Benny drove an old Maxwell automobile, a brand that went out of business in 1925. Although some details such as the car's body style and its exact model year varied over the years, what remained constant was that Benny's old car was so worn out that it would barely run, but the miserly Benny insisted he could get a few more miles out of it. Many of the sound effects for the car's clattering engine came from an actual old motor that the sound-effects shop had salvaged from a Los Angeles junkyard. When a sound-effects man missed a cue for the automobile engine, Mel Blanc quickly improvised a vocal imitation of a sputtering car engine starting up noisily that was so funny, it became a regular feature of the show.
The ongoing saga of the Maxwell was initially interrupted after just five years, when on the October 18, 1942, broadcast, Jack took his car to a local junkyard and contributed it to the World War II junk salvage drive, receiving $7.50 in war stamps in exchange. However, much of the radio audience may have remained unaware that the Maxwell was ever gone, because before long Benny was heard traveling around in a decrepit old car again, and by the end of the 1940s, his car was once more specifically identified as a Maxwell.
When  the Jack Benny Program premiered on television in 1950, a 1916 Maxwell Model 25 Tourer became one of the production's standard props. Benny's Maxwell later became a 1923 Tourer. Benny often made public appearances in Maxwells. He drove a Maxwell onto the stage in one of his last television specials.
By 1941, Jack Benny's Maxwell had become such a well-known aspect of popular culture that it was referenced in the Billy Mills song "I'm in Love with the Sound Effects Man" as heard on the June 17, 1941, Fibber McGee and Molly radio show (and later performed on a 1943 recording by Spike Jones). The automobile was also featured in the 1943 Benny film The Meanest Man in the World. Benny and his archaic auto were featured in a series of television and print ads for Texaco from the 1950s through the 1970s. A series of gags was built around the premise that Benny appreciated the value of Sky Chief brand gasoline in keeping his car running smoothly, but was too cheap to buy more than one gallon at a time. In the classic cartoon "The Mouse that Jack Built", Benny and his wife are driven by Rochester in a sputtering Maxwell car.
Many people believe that Benny appears behind the wheel of his Maxwell in the 1963 film It's a Mad, Mad, Mad, Mad World, but in fact, it was a 1932 Cadillac. The long shots for the scene were shot months before Benny was cast—with a stunt driver at the wheel—and the role was intended for Stan Laurel (which is why the character wears a derby, which Benny almost never did). When Laurel ultimately passed on appearing, Jack agreed to play the role. According to the commentary on the Criterion edition of the film, his close-ups were filmed on a rear-projection stage at the Paramount studio.
The Jack Benny Program