It’s no secret the average vehicle is getting bigger. According to data from the University of Michigan Transportation Research Institute, the average American car in 2023 was 22 inches longer and 12 inches wider than a decade before. Weight has also increased, with EPA data showing the average current heft of 4,300 lbs has increased by roughly 1,000 lbs (about 30%) since the early 1980s.
An announcement on September 19, 2024, drove the point home. That day, Hitachi Construction Machinery revealed it was replacing its EH40000AC-3 mining truck with the EH4000AC-5. Touting a best-in-class payload of 266 US tons (242 metric tons), this bad boy makes the Chevy Suburban and Jeep Grand Wagoneer look like Matchbox cars.
It also got me thinking: what are some of the most monstrous wheeled vehicles that ever saw the light of day? I don’t mean something that’s only a vehicle in a technical sense, like the famed RWE Bagger 288 bucket-wheel excavator; I’m talking about vehicles that can legitimately be driven on main roads. Here’s a sampling of some of the world’s biggest wheeled vehicles ever assembled, which include mining trucks, war-inspired machines, and pet projects of wealthy car enthusiasts.
ZIL-E167 6×6
I’ll start with a military off-road truck that, even 60-plus years later, makes other trucks seem puny. The ZIL-E167 was developed for the Soviet Union—reportedly in only two months—with the prototype completed at the end of 1962. It’s been described as a “wheeled snowmobile” made with the idea that it could handle conditions of the northernmost Soviet territories like Siberia. To do this, designers used the previous ZIL-135 to conceive a truck that measured over 30 feet long, 10 feet high, and over 10 feet wide. The 6×6 name came from its six drive wheels, and it had a pair of 7.0L V8 engines fueled by a 238-gallon gas tank.
Watching a video today of the ZIL-E167 6×6 is still a sight to behold as it maneuvers over steep hills like nothing. Even at its five-ton maximum payload, testing showed this mammoth could reach a top speed of 40 mph on the road and 19 mph in 20-inch deep water. Unfortunately, despite plans to order more units, the ZIL-E167 never made it beyond the initial prototype—purportedly because the transmission was too difficult to recreate. Nevertheless, it stands large in automotive history.
Hitachi EH4000AC-5
This historic truck, though, still pales in comparison to the Hitachi EH4000AC-5 that inspired this article. How does it achieve that 266-ton payload? With remarkable power and engineering, that’s how! The EH4000AC-5 dump truck has a Cummins QSKTA60-CE engine that generates 2,500 hp (you read that correctly). It also has a stronger suspension, and the frame and body are manufactured using the same fabrication techniques as Hitachi’s hydraulic excavators.
Overall, the EH4000AC-5 has the same dimensions as its predecessor, making it over 47 feet long and 30 feet wide. The wheels alone are 29 inches in diameter (to say nothing of the tires). Its top speed matches the ZIL-E167 ancestor at 40 mph—but befitting the modern age, you can convert this beast to full battery-electric with dynamic charging. Hitachi will begin sales sometime in 2025, so if anyone wants a massive truck, here’s the chance.
CAT 797F
While the EH4000AC-5 has the biggest payload in its class, there is a class above it—and that’s where the CAT 797F resides. The pinnacle of the 797 Series, the 797F has a nominal payload capacity of 400 US tons (363 metric tons). This mighty machine stands tall with an empty front canopy height of 25 feet 4 inches on the standard body, and it measures 31 feet 3 inches wide at the outermost rims. The CAT 797F is nearly 50 feet long, too (49.5 feet, to be exact).
Caterpillar is still making the 797F the same way as when it was unveiled in 2009, with a CAT C175-20 quad-turbo diesel engine making 4,000 gross hp. Furthermore, the gross operating weight is 1,375,000 lbs (or 1.375 million for emphasis); it’s such a heavy truck that Caterpillar needs to put 10 disc brakes per side on the front and 15 per side on the rear to safely bring it to a stop from the max speed of 42 mph. The only truck CAT makes with a bigger payload is the CAT 798, which is effectively the AC electric version of the 797F and clocks in at a 410-ton capacity.
Hummer H1 X3
The military Humvee and its street-legal off-shoots have commanded attention for their size, but there’s one Hummer that puts all of them to shame. Custom-built by the “Rainbow Sheikh” Hamad Al Nahyan, a multi-billionaire and owner of approximately 3,000 vehicles, the Hummer H1 X3 towers over everything in its path. Per the name, it’s three times bigger in every direction than the original H1, making it 21.6 feet tall, 19 feet wide, and between 46 and 52 feet long, depending on reports. Each wheel has a separate diesel engine, and the multi-level interior is so big that the Sheikh designed it like a mobile apartment complete with a kitchen and toilet.
The Hummer H1 X3 is fully drivable and reaches a top speed of 20 mph. Although the Rainbow Sheikh occasionally takes it out on public roads (always with a police escort per his standing), the rest of the time, the vehicle is displayed at the Off-Road History Museum in Al Madam, United Arab Emirates (one of four car museums the Sheikh owns). If you’re ever in the UAE, stop by and gawk at this vehicle and its 86-inch-tall tires.
BelAZ 75710
I’ve already raved about dump trucks from Hitachi and CAT, but there is an even bigger dump truck. The 75710 was developed by leading Belarus automotive manufacturer BelAZ in 2013 for the region’s mining needs, and its payload blows everything else away at 496 US tons (450 metric tons), which broke the record previously set by the 797F. Measuring 67 feet 7 inches long, 32 feet 4.62 inches wide, and 27 feet 1.25 inches high, it’s a towering presence on job sites. The truck has a pair of MTU V16 diesel-electric engines and four AC motors (two per axle) combining to generate over 4,600 hp—six times that of a Formula One car.
One of the most interesting things about this truck is the moveable axle system. This allows operators to adjust based on the payload for better weight distribution. All that and the truck weighs almost 600,000 lbs less than the 797F, making it a relative paragon of efficiency. In the most recent report, one of these trucks can be purchased for $6 million, so anyone with extreme hauling needs and a lot of disposable income can own the world’s most rugged hauler.
American Dream Limousine
A huge vehicle can still be a luxury. Don’t believe me? Let me introduce you to the American Dream limousine, the Guinness World Record holder for the longest car. First hitting roadways in 1986, it measures over 100 feet long—literally half a city block in some metropolises. Made by joining six Cadillac Eldorado luxury cars together, it weighs roughly 25,000 lbs and has two engines, 24 tires, seating for 75 people, TVs, phones, and even a built-in swimming pool and jacuzzi.
The American Dream was the brainchild of Jay Ohrberg, the same guy who designed the General Lee from “Dukes of Hazzard,” the DeLorean from the “Back to the Future” franchise, the Batmobiles for Tim Burton’s first two Batman movies, and other iconic film and TV vehicles. After falling into major disrepair in the early 21st century, the American Dream was restored in 2022 and is now fully functional. Restorers even added a helipad so you can land aircraft on it.
The Continued Growth of Vehicles
Even the biggest everyday road vehicles like heavy-duty pickups, full-size SUVs, and cargo vans are no match for a designer’s imagination. Whether for practical purposes or to show off, there have been some colossal vehicles over the decades—and who knows what may come next! I may never get to drive one of them (the EPA would frown at the fuel economy), but I’ll certainly be admiring the ingenuity from afar.
