BMW builds cars on monocoque platforms. That’s been true for decades — from the E30 to the CLAR architecture underpinning everything from the G20 3 Series to the G70 7 Series. So when a patent surfaces showing BMW engineering a ladder frame chassis, it will certainly catch our attention.
The patent, filed with Germany’s DPMA under file number DE 10 2024 130 768.4 and first spotted by CarBuzz, was submitted in 2024 but only published at the end of April 2026. Ladder frames are the structural backbone of body-on-frame vehicles: the Mercedes G-Class, the Land Rover Defender, every American full-size pickup on sale today. BMW has never used one in a modern production car.
What The Patent Actually Describes
The design is built around simplicity and scalability, you can see it here. The diagonal connecting elements between the floor assembly and the front and rear sections can be identical on both ends — same part, front and back. The front and rear crossmembers can be the same part as well. Individual profiles are cut from long beams, which means adding or subtracting a few centimeters in length or width is a straightforward operation. The connecting elements carry over unchanged. That kind of modularity is what makes a platform genuinely scalable rather than theoretically scalable.
Material choices go beyond steel and aluminum. The patent mentions fiber-reinforced plastic — including carbon fiber — as a possibility for the cross and longitudinal beams. Whether that shows up in any production version is a separate question, but it’s not window dressing: FRP beams would meaningfully reduce unsprung weight in a body-on-frame structure that would otherwise trend heavy.
Designed for EVs, Not Combustion
Here’s the detail that stands out. The patent explicitly addresses the ladder frame’s suitability for electric cars, including the installation of drive batteries and electric motors. It does not mention conventional combustion engines at all. A body-on-frame EV isn’t a contradiction — the Rivian R1T and R1S prove the concept works, and both are serious off-road performers. But it does narrow the field of likely candidates. BMW isn’t going to build a ladder-frame electric sedan. What they might build is something meant to go places that a CLAR-based X5 can’t.
Will BMW Give Us A True Off-Roader?
BMW has been rumored for months to be working on a project internally called the BMW Rugged, chassis code G74 — a Munich-built answer to the G-Class and the Defender. Both of those vehicles use ladder frames. Both sell extremely well to buyers who actually use them off-road, and to a much larger group of buyers who like the idea that they could.
The G74 is the obvious candidate. The timing fits: a 2024 patent filing published in 2026 lines up with a vehicle that could reach production by 2030, if approved. The scalability language in the patent would make sense for a platform intended to spawn multiple body styles, which is exactly what you’d want if you’re trying to compete with Land Rover’s lineup rather than just the Defender specifically.
But it’s also worth saying plainly: BMW files patents on technologies it never builds. This could be a defensive filing, a hedge against a competitor, or an engineering exercise that stays internal. The patent is broad enough to apply to almost anything — the document says the frame suits “sedan, SUV, station wagon, compact, hatchback, convertible” — which is either impressively flexible or a sign that no one has decided what it’s actually for yet.
If the G74 is real and uses this platform, BMW would be entering a segment where heritage matters enormously. The G-Class has been in continuous production since 1979. The Defender name goes back to 1983. BMW has no equivalent history to lean on, which means the product itself has to carry the argument.
A well-engineered electric ladder-frame platform — scalable, light enough to not be a rolling anchor, capable off-road — could do that. Whether this patent becomes that platform, or stays in a filing cabinet in Munich, is still an open question.
[Source: DPMA via Carbuzz]
