"The most dangerous part of an automobile is the nut…

“The most dangerous part of an automobile is the nut behind the wheel” is an old saying about auto safety. The “nut” is the driver. The following poem was in the Brooklyn (NY) Standard Union on December 10, 1922:

There are many troublesome things
about the kicker’s automobile.
But the one that troubles most is the
nut behind the wheel.

“The automobile is an innocent enough machine, but it is the nut behind the wheel that causes the trouble” was cited in 1929. Another poem was printed in the Cleveland (OH) Plain Dealer on November 17, 1930:

Of all the auto parts
That cause the accidents, we feel
That what’s to blame for most of them
Is the nut behind the wheel.

Old Fulton NY Post Cards
10 December 1922, Brooklyn (NY) Standard Union, “C.K.‘s Filling Station,” pg. 21, col. 5:
There are many troublesome things
about the kicker’s automobile.
But the one that troubles most is the
nut behind the wheel.

6 February 1929, The Daily Northwestern (Oshkosh, WI), “Eternal Vigilance Is Price Demanded to Secure Safety,” pg. 5, col. 2:
“The automobile is an innocent enough machine, but it is the nut behind the wheel that causes the trouble.”
(C. F. Otto, Wasau, before the Oshkosh Industrial Safety school.—ed.)

5 August 1929, Oakland (CA) Tribune, “Benefits of Education” by Keel Edward, pg. 20, col. 3:
Tho Nut behind The Wheel is the cause of most traffic jams!

17 November 1930, Cleveland (OH) Plain Dealer, “Philosopher of Folly’s Column,” pg. 10, col. 3:
Of all the auto parts
That cause the accidents, we feel
That what’s to blame for most of them
Is the nut behind the wheel.
MR. AND MRS.

Google News Archive
9 June 1950, Pittsburgh (PA) Post-Gazette, “The People Speak,” pg. 14, col. 4:
Don’t be guilty of being that awful “Nut Behind the Wheel.”
JANE PERRY
Ligonier, Pa.

Google News Archive
5 February 1952, The Times-News (Hendersonville, NC), pg. 2, col. 1:
THE WEAKEST PART IN AN AUTO IS THE NUT BEHIND THE WHEEL
By Brian Biossat

Google News Archive
26 April 1958, The Independent (St. Petersburg, FL), “Nut Behind The Wheel” (editorial), pg. 8-A, col. 1:
Few things more accurately reflect our strange highway crackup habits than the annual statistics issued by the Travelers Insurance Companies of Hartford, Conn.

Google News Archive
24 December 1958, Ottawa (Ontario) Citizen, “Even A Little Drinking Will Impair Driver’s Ability To Handle His Car” by Dr. Leon A. Greenberg, pg. 7, col. 3:
Automobiles are sleeker, faster, more powerful, more mechanically foolproof than ever. But there is one motoring component that the engineer can do nothing about—the “nut” behind the wheel—whose effectiveness has been shaded down by alcohol.

Google Books
16 April 1966, Victoria (TX) Advocate, “The Nut Behind the Wheel?” (editorial), pg. 4, col. 1:
“It’s not the cars that cause accidents in the overwhelming number of cases,” said Traffic Commissioner Henry Barnes of New York. “It’s the loose nut behind the wheel.”

Google Books
1001 Really Stupid Jokes
By Mike Phillips
London: Robinson Children’s Books
2000
Pg. ?:
If you watch the way that many motorists drive you will soon reach the conclusion that the most dangerous part of a car is the nut behind the wheel.

Google Books
Homicide:
A Sociological Explanation
By Leonard Beeghley
Lanham, MD: Rowman & Littlefield
2003
Pg. 12:
The National Safety Council argued that “the most dangerous part of an automobile is the nut behind the wheel.”

Twitter
Carlton Reid
‏@carltonreid
Most dangerous part on a car? Nut behind the wheel. Gov’t greenlights driverless cars on UK roads: https://www.gov.uk/government/news/uk-government-fast-tracks-driverless-cars …
5:45 AM - 30 Jul 2014

PC Mag
Mobile Threat Monday: The Most Sophisticated Android Botnet
Nov 24, 2014 3:58 PM EST
By Neil J. Rubenking
(...)
There’s an old saying that the most dangerous component of an automobile is the nut behind the wheel.