A mule car is a current vehicle that has been heavily modified with parts from a new design for testing and development purposes. You make as many changes to a mule as you need to, to make it representative for the tests you want. The term 'Mule' has only been applied to vehicles where the purpose of the body shell is to act as a vehicle to carry engine/transmission/suspension development actions. Hence the Mule just carries the parts. Most mules are for ride and handling, road loads, and powertrain/driveline work. (Info from: https://www.eng-tips.com/viewthread.cfm?qid=199247)
I just found this one today, but I have no idea where the term originated.
Interesting. I did some consulting at Ford in the late 1980's. Personally I don't remember hearing the term, but I did hear 'buck' and 'master buck'. I was working at Rotunda and the 'master buck' was there. It was essentially a frame and they built it into a completed car as they got prototype parts in.
I remember buck also. To my recollection, the buck focused more on the body and not on the drive train. Mules focused on drive train and instrumentation to take measurements. I drove one once and the entire vehicle interior was covered in wires. Only the drivers seat area was free of wires.
You are probably right. I was mainly there to advise their entertainment system design engineers. I only saw the 'master buck' on a brief 'tour' of the facility one of the engineers gave me one day. I really don't remember too much about it. Most of my interface with the engineers was via phone and mail/package services. I reviewed circuit card assembly designs and did vibration and other environmental analysis and tests. I also did some work with their potted engine control modules, mainly with regard to heat and vibration. I enjoyed working with them.
Mule is a term used to describe a quasi equivalent functional representation of a new vehicle, device etc....so where I live from time to time one can see "Big Three" Mules on the roads, the body or outside structure might appear to be a current model say Blazer...but underneath is a totally new powertrain interior etc...so its a working model of an upcoming new platform. And its purpose is to vett the new concept/model etc typically during the Prototype stage of the APQP process...great site!!