Actually I do not think I am very well qualified at this point, I have only the first impression of the HMMWV, I do have allot of experience with the Unimog, mostly the 404s, and I did own a 424 for a couple years.
I used to be an "agent" for a man that imported 404s of all configurations, I would go pick them up at the roll/roll port in Galveston and bring them to Baytown where I would prepare, service and in some cases modify them for whatever life they had ahead of them, I handled dozens of them, many times trailering one while the wife and or volunteers would drive the others for the 50mi run to the shop, I have built engines, transplanted higher HP engines and have done diesel conversions along with all the other maintenance items that need attention.
The biggest issue with the 404 is they are under powered, the original M180 (2.2L@80HP) was and is fine for off road but pretty anemic on the US roads, The last gasser I owned had a M130 (2.8L@160HP) installed in it (was in the 1995 Four Wheeler top truck challenge) The wife and I would load the M422A1 in the bed and pull a small pop up camper to Jeep Jamborees all over the south and did not suffer too much road rage along the way. ( I have also run Gama Goat 11.00-18 ND tires on all my personal 404s)
Of course the 404 is a late 50s/early60s design, no power or disk brakes, but they stop just fine. Another short coming of the 404 is poor transmission synchronization which is compounded by many users filling the transmission with GL5 gear lube that eats yellow metal, it does not take much practice to learn to double clutch and make shifting a smooth process.
So back to my first and ONLY impression of the HMMWV SO SOME OF THESE IMPRESSIONS MAY BE ACTUAL PROBLEMS WITH THIS MACHINE! although the Unimogs were VERY predictable on performance from one to the next.
It steers like you are guiding a ball with a stick, it stays wherever you leave the steering wheel as if it has no castor at all in the front end, on the other hand even without PS the Unimog steers very well as long as it is moving at all. (my diesel 404 has huge PTO winch on the front so I added Air-O-Matic steering)
The HMMWV rides like a brick on a skate board, unlike the Unimog which has a very smooth suspension. most people do not know (and some make REALLY bad decisions when modifying the 404) is that everything articulates within the frame, cab, engine, bed, that is why the Unimog is much superior to any other stock vehicle in axle articulation, the frame twist becomes part of the suspension.
EVERYTHING on the HMMWV rattles, the doors on a Unimog close like a MERCEDES door, no big clunks no rattles.
The HMWV is very noisy, I am sure this is compounded by mine having a full body and the fact that the pumpkins are mounted to the chassis would make them inherently noisier and the tires!!
No air flow, even though the 404 was designed for service in Europe it has much better ventilation than the HMMWV, on the HMMWV I had the passenger side vent open but I am not sure the water was cut completely off to the heater core, the heat is no doubt influenced by the aluminum body which conducts heat much better than steel, the dash was HOT to the touch, this of course this needs farther investigation.
AGAIN I only have any experience with this one machine but I do not understand what everyone is talking about the HMMWV being under powered, it would hum along just fine at 62-65 with tons of pedal left, no problems with the admittedly small hills and overpasses along the way, again just this machine and unloaded.
The "slack" inherent by having inboard brakes is the same as my M422A1 had.
That constant buzzing noise from the right tires running down the rumble strips on the Shoulder of the road is a little annoying.......
So please no hate, just an old mans first impression of the HMMWV and I was asked..
Mogman