Here is a promo for the first Jeep, and as near as we can tell, the first use of the word "Jeep" in any newspaper in America, from the Newark Advocate, March 16, 1936, by way of Newspapers.com. It's not talking about a 4x4 truck, of course, but Eugene the Jeep, the magical dog that appeared in 1936 in The Thimble Theater, starring Popeye, a daily comic strip by E.C. Segar, the creator of the original Popeye cartoon strip which appeared in hundreds of newspapers in the 1930s. After World War II, the Federal Trade Commission, in researching the history of the word "Jeep" as part of the trademark application by Willys-Overland for the name, determined that "Jeep" had originated with the cartoon strip.
As stated elsewhere on here.. The name came from the thousands of men in our Amazing armed forces who drove the little General purpose (GP) vehicles to victory! GP, say it three times fast, it's a "Jeep". Now, Eugene was cute but very obscure and only seen in certain areas of the country.. Not even close to the amount of people that called the GP=Jeep.
My father learned to drive on a Jeep on one of the two US bases in the USSR, where he served as a radar mechanic for the shuttle bombing (photo below). His teacher was a race car driver, who said, "the trouble with these Jeeps is you can get 'em up on two wheels, but you're never sure if you can get them back down again," scaring the piss out of my father.
There was another recent article here on Hagerty about this Jeep name thing.
The model on the paperwork is MB or GPW (Ford made the GPW and made a lot of them --about 40% of total wartime Jeeps).
You get the GP from the motorpool.
It's not a reach that GP becomes Jeep in common soldier slang. Sounds better than an "Emby"
Eugene the Jeep smells like a coincidence to me --that's giving a lot of credit for pop-culture penetration of a 1936 Popeye comic strip. 1938 for 1st cartoon short, 1940 for the 2nd. Bantam prototype project was circa 1940.
Then again, maybe one smart-aleck comic strip fan wanted their favorite Popeye character to live forever as a vehicle...
The trademark search is a standard thing. All sorts of bands (for example) have had to change their name for US market because someone, somewhen in part of the country used that name. Doesn't matter that it was a tiny regional band and you are the hugest thing from somewhere else.