Step By Step
The most striking difference between the civilian and military Hummers is the interior. The military version is far more spartan compared to the leather seats and optional carbon-fiber inlays all over a civilian unit, but the differences extend beyond amenities. The dash layout is totally different, as are the gauges, the number of controls, and the steering wheel. We have to admit we like the military steering wheel better, and the dash layout goes better with the Hummer’s no-frills exterior.
The two share the same parking brake, transfer case, and transmission shift levers, although a civilian Hummer receives vinyl-covered, padded interior panels to gussy it up a bit. The parking brake lever is military-inspired and offers a very positive engagement. Adjusting the parking brake is done by simply turning the knob at the top. All Hummers have full-time four-wheel drive, so the positions in both versions are marked H (High), HL (High Loc), N (neutral), and L (Low-Loc). Interestingly, there is no Park position on the military versions, and we’re told the civilian Hummers are the first to have Park. In order to start any Hummer without a Park position, it’s necessary to set the parking brake and shift the tranny into Neutral. No manuals are available in either version, and all the automatics are GM four-speed 4L80Es.
Military Hummers don’t have a keyed ignition switch. Instead, a three-position lever controls off, run, and start (the high-tech anti-theft system involves pulling a steel cable out from under the dash, wrapping it around the steering wheel, and securing it with a padlock). The light switch is also military spec, and it’s located just below the ignition switch. The indicator to the right of the ignition switch is an air-filter restriction gauge, something that’s not found inside the civilian version. A regular keyed ignition on the steering column is used on civilian units.
Everything under the hood is pretty much the same when comparing the civilian and military 6.2L diesel engines. However, there are a few notable exceptions. Military Hummers don’t have air conditioning, run on a 24-volt electrical system, and have a giant generator hanging off the engine. For those equipped with a central tire-inflation system (optional on both the civilian and the military Hummers), the compressor and solenoids are located on the driver-side fenderwell. Civilians have the option of a GM 6.5L diesel, a 6.5L turbodiesel, or a 5.7L gas engine.
The fiberglass hoods are interchangeable between the two versions, right down to the mounting pad for the blackout light (the blackout light is absent on the civilian Hummer, of course). The military version has different parking and taillights, and the lighting system actually has two blackout stages. The first stage leaves the lower portion of the two parking lights and taillights illuminated, while the full blackout only illuminates a single small light on the front that’s about the strength of a small flashlight bulb. This light enables the driver to see about 40 feet ahead of the truck with the aid of military-spec night-vision goggles.
The military uses several different bodies on the Hummer, including an ambulance, a light-duty cargo carrier, a light-duty passenger carrier, and a heavy-duty cargo carrier. Civilian models are also available in a variety of styles, including a two- or four-door hardtop, a two- or four-door soft top, and a four-door wagon. Both military and civilian Hummers have a 1-1/4-ton rating, and all military models come standard with a pintle hitch. There’s a spot tucked under the vehicle ahead of the hitch for a shovel and an ax that’s not found on civilian models.
Both styles use the same suspension and drivetrain designs. The suspension is independent front and rear and sprung with coils at each wheel, which yields an impressive 16 inches of ground clearance in the center of the vehicle. However, we noted wheel travel is limited, especially when compared to conventional straight-axle designs. The Hummer features 1.92:1 gear reduction units at each wheel, which is technology borrowed from heavy-duty trucks. By using these reduction units at the extreme end of the driveline, it’s possible to use smaller and lighter components throughout the rest of the drivetrain. Also, instead of having the brakes at each wheel like most vehicles, the Hummer’s all-disc brakes are located at the end of the differential assembly on the upper portion of the axleshafts. The only difference between the two models is different spring rates and shock valving, which also vary according to the body.
There are very few options to be had on military Hummers, but one is a deep-fording kit. Both Hummer styles feature a canister-type air cleaner located on the passenger-side fenderwell, and air is taken in through the large fitting mounted at the base of the windshield as shown. The deep-fording kit extends the height of the intake to the top of the windshield in the front and the tailpipe is extended to approximately the same height in the rear.
Another option on civilian models is a 12,000-pound Warn electric winch mounted in a cradle that doesn’t reduce the approach angle as much as other winch mounts we’ve seen. The tow loops on the front are standard and shared with the military trucks. A few military Hummers have winches, but they’re specially made to military specs.
How would you like to spend 12 hours bouncing around the woods while sitting in this seat? It’s obvious that soldier comfort isn’t a high priority to the military. However, eliminating the extra foam and power-adjustable seats frees up room for a storage box under the military seat, similar to the old passenger Jeep seats.
Whenever a group of four-wheelers starts talking about Hummers, the conversation inevitably turns into a debate over the differences between civilian and military versions. Some people claim that the two are virtually identical except for a few more creature comforts inside the civilian model, while others swear the two models share almost nothing. We have to admit we were curious too, so after we had a chance to get up close and personal with typical mil-spec HMMWVs (see "Driving Uncle Sam," Oct. '98), we couldn't wait to crawl all over a civilian version and find out the truth.
So what did we find? For starters, military and civilian Humvees are basically the same underneath. Same diffs, same axleshafts, same transmissions, same transfer cases, and same basic suspension components. The only functional variants include three engine choices and 12-volt electrical systems for civilian models (one engine choice and 24-volt electrical systems for the military) and slightly different spring rates, shocks, and tires. In fact, a representative at AM General told us that all Hummer chassis come off the same factory line and are then finished differently depending on their final destination. So when your buddies try to convince you that civilian models aren't as strong, tell them you know better.
The biggest difference is obvious: The interiors are worlds apart. While the spartan military-issue interior is dominated by a giant radio and features cool canvas seats, the civilian model can include comfortable leather seats, carbon-fiber dash inserts, and enough creature comforts, doo-dads, and gadgets to help justify the hefty $65,000-plus pricetag. Civilian models have completely different dashes filled with gauges that we suspect have been borrowed from semitrucks and have lots of trim for a finished look. All you get on military ones is uncovered aluminum and a simple uncluttered dash.
So after all is said and done, which one is preferable? Since the drivetrain and suspension are the same, the question is really how much leather do you want? If youre looking to make the ultimate urban statement, then a civilian Hummer is probably perfect for you. If you want to wheel the thing hard and not worry about getting the inside muddy, then youd be all over a military one.