It is plausible that the origin was mixed and converged on "jeep" from multiple directions. Ford Motor Company pushed its Ford GP hard, to get the military contract, putting the term "GP" into use. Military officers and G.I.s involved in the procurement and testing of the car may have called it jeep from the WWI slang. Civilian contractors, engineers, and testers may have related it to Popeye's "Eugene the Jeep" character. People may have heard the same name from different directions, and as one person heard it from another, put their own understanding and explanation on it. Overwhelming presence of the nickname 'jeep' in the public's opinion was probably the deciding factor.