So there are some vehicles that are clearly derived from real-world machines. There are some that are obvious, some that elude classification, and some that are merely inspired by real-life vehicles. Nonetheless, they are almost always modified enough to distinguish them from their real-world counterparts.
Being a 3D modeler, specializing in vehicles of all types, I have gone through extensive research to get to the truth about some of the more ambiguous ones.
First, the list of the obvious vehicles, and their real-world counter-parts:
*although the toys would be really poor representations of the real-world models, these observations are based from all the styling, functional, and practical cues that line up amidst fact and fantasy.
VAMP - Lamborghini Cheetah. Modifications: Shortened wheel-base, bigger rectangle headlights, computer-sync anti-personnel gun, front engine, minor body details.
** More research data reveals that the VAMP was also heavily influenced by the FMC XR-311. Note the fender colors and pattern on the wheel mags on the illustration. The Cheetah itself was also designed in favor of the looks of this vehicle.
Stinger - again the Lamborghini Cheetah. Modifications: Shortened wheel-base, bigger rectangle headlights, anti-air missiles, front engine, minor body details. While the look of the Stinger was taken from the Cheetah or XR-311, the tactical role it plays was most probably derived from the Avenger, an anti-air version of the HMMWV (Humvee). The name 'Stinger' was even jacked by the type of missiles that the Avenger fires - Stingers.
RAM - Honda CB 450 "Hawk". Mods: Vulcan 20mm sidecar, gunner's cowling (over what could have been handlebars suitable for driving and gunning simultaneously), 6-star mags. It could possibly be a CB 400 Hawk. Aside from the exhaust pipes layout, it could also have been a CB 750, CB 900 or CB 1100. The old CB 900 F2 even had a cowling that very closely resembles the RAM's. The RAM's blueprints suggest that it's a CB 1000 (due to its 1000cc engine), which there wasn't such a thing for the Honda CB series of that time.
Note: If not for this usage of the RAM mold, I would not have known to look for motorcycles with the name "hawk" in them, which lead me to the CB 400 and CB 450 through reverse-heritage searching. Mounting a gun on a motorcycle is too generic of an operation, so the model of motorcycle and gun are important here.
Skystriker - Grumman F-14 Tomcat. Mods: Possible higher flight ceiling, weapon configuration and carrying capacity, nose cannon moved to top (but how?).
Rattler - Fairchild-Republic A-10 Thunderbolt II, aka 'Warthog'. Mods: Main engines relocated to tilted wings for VTOL capabilities, a third engine added to the tail section, slanted tail stabilizers, dorsal-mounted gunner station, spotlights. Other influences: North American B-25. The B-25 and the A-10 already share a lot of styling cues as it is. The most notable is the double tail fins on the extremes of the elevator wings, but there's also the elongated tail and wide wingspan (I don't know how they measure to each other, but we're talking proportions here). Of course, the Rattler gets the dorsal guns from the B-25.
Dragonfly - Bell AH-1 Cobra. Mods: Tow hook, NOTOR (No Tail Rotor system), side-mounted 160mm cannon (unrealistic caliber), unrealistic pilot /co-pilot position swap, unrealistic pilot gun (position and caliber), quad exhaust (this was not intended to be a Super-Cobra). Chin turret config is standard.
Storm Eagle - Northrop/McDonnell Douglas YF-23. Mods: Nothing significant. The missiles are mounted outside of the hull on the toy. This may simply be due to size and cost limitations.
Liquidator - Saab 35 Draken. Mods: Nothing significant.
Ghoststriker X-16 - Lockheed Martin F-16. Mods: Just the usual landing-gear-popping-out-of-the-turbofan syndrome.
Hammer - AM General HMMWV. Mods: severely customized main body, unusual weapon arrangement and selection.
It's fun to note that this toy's name gets inspiration from the name of the civilian version of the vehicle - 'Hummer'. The phrase was popularized by a certain Austrian body builder/movie star/former California governor among other people, long before the Hummer company came about.
Warthog AIFV - FMC Corporation AAV-7A1. Mods: Anti-personnel weaponry, including two top-mounted anti-infantry missiles.
APC - Véhicule de l'Avant Blindé, or VAB. Mods: roof converted to soft top, gun turret moved to the center, underwater access doors added, smaller and wider wheels, third axle added; thus more passenger seating available. The APC may have been derived from a 6x6 version of the VAB. Though, the 4-wheel version has a box-like shape similar to the GI Joe APC's "watertight hull entry hatch."
Note: The GI Joe APC may have had influences from other APCs. All wheeled APCs are very similar in styling (as opposed to tracked APCs), but the subtle nuances of the nose and lower hull make the VAB the winner, even more so than the Sisu XA-180.
Mauler MBT - AAI RDF/LT. Mods: Lengthened, widened, extra pair of ground wheels added, cannon caliber increased to 125mm (but this is more likely to be the length of the shell, rather than the diameter), various computer components, engine supercharger vents. The side skirt armor is heavily influenced by the M1 Abrams series armor.
Note: This one was hard to find any information on. For the longest time, I thought the Mauler was a prototype of the M1 (or M1A1, M1A2) Abrams. Upon discovering the RDF/LT, the toy is actually more to scale as such than it would have been if comparing it to the Abrams. At this size and weight, it can be carried by a Tomahawk.
The not-so-obvious and inspired vehicles:
MOBAT - It's hard to place an exact match on this vehicle. It has a lot of influence from a few different tanks/tank prototypes, but I believe it to be unique enough to distinguish itself from any actual vehicle. There is a heavy dose of the modified, international versions of an M60, such as this Turkish M60 or this Israeli M60, called the Magach 7. The main turret looks like it borrows style from the international M60 and the MBT70. The combination of styling and external features sets it part, and on both accounts are very much updated from the original forms of any of these tanks, for certain.
AWE Striker - It sort of resembles the Chenowth FAV. Taking a closer look at the frame design, it could also be based on a Berrien Stalker. Mods: Top-mounted "70mm launcher" with remote hand-held targeting device, "woods buggy" configuration (four same-size wheels and tires), engine cover with cooling fan. Chenowth actually made a version of their FAV with a two-man crew and a TOW. The "70mm Launcher" mentioned on the AWE Striker's blueprint sheet looks sort of like a TOW, but is probably a jumbo grenade launcher.
Flight Pod (Trubble Bubble) - Take the helicopter rotors and tail away from the Korean War era H-13 Sioux (these choppers were frequently on the show, "M*A*S*H"), and look just at the canopy section. Although the cut-away areas of its canopy are designed differently, the bubble concept is the same. The Sioux was a two-man, side-by-side job, whereas the 'pod is supposed to be for one in the center. When you look at the control console for the Sioux, you'll notice it is narrow and right up the center, rather than in front of one of the seats - very similar to the 'pod. It also shares the curling, "come here" finger shape the 'pod's console has. The over-simplified square seat cushion seems to further add to the connection.
Maggot - UDES XX20 and possibly the BvS 10. The two components' positions are swapped, but the concept is the same. UPDATE: The Maggot design seems like it could also have been inspired by any Self-propelled Artillery, and then split up like the UDES XX20.
HAVOC - the 'A' in HAVOC stands for Articulated. Taking that into consideration and giving it an overall look, it could have originally developed from the same influences as the Maggot. It could also have very well been derived from some real-life Snow Cat vehicles. As an ironic side note, the GI Joe Snow Cat is mostly a unique vehicle, as far as I can tell. It looks more like a 10-wheeler with treads (that's an 18-wheeler without the trailer), than a real half-track.
Moray - Is probably meant to be a cross between a PT Boat and a Cigarette Boat. The Moray uses hydrofoil technology, which exists in real-life military boats like the USS Plainview and the HMCS Bras d'Or (Brass Door?).
Thunder Machine - Uses the nose of a '78 Firebird Trans-Am (here's a similar 1981 T/A). This rest is a hodge-podge of junk formed together, Mad Max style. According to an Action Force compendium, it uses parts from the HISS, Stinger, Mamba, Moray, and some old US Jets. The guns are M-61s, and the siren lights are typical 1980s cruiser lights.
Night Raven - This is heavily inspired by the Lockheed M-21/D-21 system. Under careful scrutiny, one can easily spot the physical design differences, yet still affirm the influence. There was also a fictional MiG 31 Firefox (not to be confused with the real-life MiG 31 Foxhound). The styling of the Raven more closely resembles the Firefox, but the actual wing/engine configuration does not.
X30 Conquest - This may have been an attempt to make the successor of the real-life Grumman X29 concept, which was based off of the F-5 Freedom Fighter platform. The X30 Conquest looks as though it were intended to be based off the F/A-18 Hornet platform, using and improving upon the same forward-swept wing design principles as the X29.
Polar Battle Bear - Raider Snowmobiles were just one of a few companies that would make twin-track sleds. The PBB was probably heavily inspired by Raider's models, and then fitted with military hardware.
Thunderclap - heavily influenced by Atomic Annie. The tractors and some other details are enough of a difference to put it into this category.
Bridgelayer - There are real world examples of this vehicle having been used throughout the latter half of the 1900's. The Soviet T-55 and T-72 have both been fitted with the unfolding bridge, and recently the US M60A1 has been designed for just that purpose. It is my opinion, however, that the base was inspired by the UDES 21 chassis. The overall contour of the vehicle has a very low-detail wedge shape, and then levels off at the top. It also sports side armor. add two big Xs on each fender and it looks strikingly like the TnC.
Bridge - Though bridges come in a few shapes and sizes, the Toss 'N Cross' bridge has similar design as the one on this German M48A2-AVLB.
USS Flagg - Nimitz-class US Aircraft Carrier. Due to the grossly inaccurate scale of the toy, this is just an educated guess. The Nimitz-class is big enough to fit a suitable amount of F-14s on the deck and on the service level. In this editor's opinion, however, a Nimitz-sized AC for the GI Joes is a little over-the-top. Other contributors to this thread have suggested Forrestal class carriers and Kitty Hawk class carriers as influence. Either of which support and adequate size and shape.
Killer WHALE - The Griffon 470TD has a huge influence on the WHALE's design. The GI Joe hovercraft has a rear driver position added to the topside, and the front compartment has been converted to accommodate personnel or cargo, which are loaded from the front. The WHALE is attempting to do with the smaller 470TD proportions what the hovercraft on this page demonstrates on a larger scale, and by my accounts it succeeds in that fusion.
Mamba - This uses a real-world type of rotary system called intermeshing rotors. Because the rotors are going in opposite directions of one another, there is no need for a tail rotor to counter the turning effect of traditional single-rotor helos. At this point, it is uncertain what influenced the inclusion of the deployable side-craft.
Buzz Boar - There have been motorized vehicles called monowheels for decades, now, but the Buzz Boar also digs and burrows into the ground. The idea of an unbraced wheel doing this on its own is a little more far-fetched than many other strange GI Joe concepts, but it has a really cool practical value. The idea of using one for military purposes and covering it up may have come from this Popular Science article. This researcher would go so far as to say that even the concept of burrowing came from this article. The Buzz Boar designers probably saw that the vehicle's poles dig into the ground like ski poles, and took it to an extreme level of the whole rig digging into the ground.
Manta - This is basically a modified windsurf board, with a side-pontoon for carrying a torpedo and a machine gun on the handlebar.
Phantom F-19 - There are two completely different design versions of the real-world F-19, and both of them are conceptual. The GI Joe jet is based on the more popularly known version of the two. Other than GI Joe, the only known incarnations of these craft are model kits.
Skystorm - Lacking any other influences for its futuristic styling, the Skystorm at least draws functional design cues from the Sikorsky S-72, a real-life X-wing chopper that can also fly like a jet, without the use of the main rotor for lift.
Swamp Smasher - This might be a stretch, but considering the Landmaster was created about a decade before the Swamp Smasher, there is at least some influence transpiring. It may also be patterned after lunar and extra-terrestrial rover concept designs.
Chameleon - The idea of this vehicle is not as outrageous as one might think, though the design is bit on the impractical side. The Wetbike Tomcat was introduced in 1978 and was considered something for advanced riders. This was before the term "personal watercraft" was used to identify the category. As you can see, the Wetbike has a pair of skis, which basically hydroplane the vehicle at speed. When still, the vehicle lowers into the water. The Chameleon's functional concept is a tad different. There is a small turbofan jet mounted under the chassis and raised from the skis, rather than a water jet sitting on the water. It's as if the bike were expected to float on its skis at all times. Well, they would have to be big wooden skis in order to pull that off. What makes the two connected has to be the fact that there is steering which manipulates two (or two pairs of) surfaces making water contact.
Water Moccasin - It seems like this is an original design. However, the concept of an airboat is not far-fetched at all. I suspect the designers added the split in the front of the boat so that the driver can see. A traditional airboat would have the driver sitting about where the Water Moccasin's turret is, while passengers and/or crew would be in the front, under the driver's view, theater-seating-style.
Armadillo - Although it doesn't suit the same purpose, the WWII-era M4 Sherman lends its main hull for inspiration to the Armadillo. Scaled down and backwards, the M4 hull is placed on a proportionately smaller set of tracks and is mounted by what looks like an anti-aircraft gun system turret.
Firebat - Tiny, manned jets do exist. In fact, I'd wager that the BD-5J is even smaller than a real-life Firebat would be. Similar in design is the Pulse LiteStar, which may also have had some an impact on the Firebat's looks. What's interesting is that it is a car inspired by aircraft and/or aerodynamics. The Firebat's hull may have been influenced by this minimal-curve, tapered shape. The functional concept (and maybe a little bit of the design) must have come from the Ryan X-13, which can take off while facing skyward, level out for traditional flight, and then lean back and land while facing skyward again.
Tomahawk - A casual glance at the Tomahawk coupled with a casual knowledge base of helicopters might lead one to instantly mistake it as a CH-47 Chinook. Taking a more discriminating look, we find however it is mostly a "Frankensteining" of two other helicopters: the Sikorsky S-61 Sea King and the Piasecki H-21B. The S-61 is especially notable in the blades-per-rotor and in the turbine housing - without the air intake guard. The landing gear layout is also very similar. The H-21B influenced the Tomahawk's tail section - the upward shift in the fuselage and the use of side stabilizers. Although the front and rear rotor assemblies look to be derived from the S-61, the fact that there are two of them is the most important detail this bird has borrowed from the H-21B. Of course, there are other details that seem to be tacked on as afterthoughts, such as the chin turret mini-gun, the aileron missiles, and the strange and unnecessary anti-torque tail rotor.
Stationary and Remote-Controlled Equipment:
The stationary weapons in GI Joe are puzzling. They are often easy to identify, but usually discovered to61 be based on older weapons. Often these older weapons might be retro-fitted with modern computer systems for targeting and automatic firing capacity or whatnot. GI Joe is known for its hi-tech and alternative equipment, but then here are a lot of antiquated and traditional style weapons. Whether they are useful in a real battle scenario or not is up for debate.
Mountain Howitzer - US M101A1 Howitzer. WWII era howitzer that may have been still very useful in the 1980's.
FLAK - perhaps influenced most by the German 88mm Anti-Aircraft FlaK. Although the main construction seems very modernized, the overall look is the same. There is a chair placed on this one, as well as the obligatory GI Joe computer system upgrade.
Whirlwind - For the life of me, I cannot find the image, but there was a single gun system version of this machine in real life. The image was pretty good quality, too. I can't remember what the name designation was, either. Pretty much the only differences are the extra M61 and a computer system. On the original machine, the single M61 was centered in front of the gunner.
MMS - is a MIM-23 HAWK. On the MIM-23, the trailer is actually a cart that the system can be removed from. Later, a PAC/RAT-ish treaded vehicle could automate the loading of the missiles and/or tow the cart. The robotic vehicle was controlled remotely by a near-by crewman.
PAC/RAT (missiles) - The WWII era Borgward Automotive Goliath Tracked Mine appears to have some serious influence on the chassis of the Missile PAC/RAT.
**Folks, feel free to add your knowledge and/or submit corrections to this thread. We will also be tossing around ideas for some of the ambiguous vehicles. I'll edit this post with confirmed information when free time permits. If you find this stuff interesting like I do, then I want to hear from you!
Many thanks go to the members who have contributed with fact finding and knowledge sharing. This has grown well beyond the scope of what I started, as I expected it to. A special thanks to those of you taking the time and interest to read this thread, and to those of you participating in the discussions.