GM stated that it has successfully tested every prototype of the 4.5L Duramax V8 engine, with one currently located in Sweden.

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      Nearly twenty years ago, General Motors was on the cusp of unveiling a groundbreaking engine that might have transformed the pickup truck landscape. However, it never came to fruition.

      The 4.5-liter turbodiesel V8, known as the Baby Duramax, was almost production-ready. It was even showcased in a Suburban as a concept at a SEMA show, poised to set new standards in the half-ton truck class. But then came the 2008 crash, GM entered bankruptcy, and the Baby Duramax was put on ice. GM claimed all prototypes were destroyed, yet at least one made its way out into the world, ending up in Sweden.

      This isn't an exaggeration. The Baby Duramax promised more torque than any half-ton engine available at the time, superior fuel economy compared to competitors' less powerful engines, and cutting-edge technology that wouldn’t be seen in sports cars for another decade. It was an engineering feat that seems to have been far ahead of its era. What could have been—or could still be, considering at least one prototype still exists—raises questions. Are there more? How many? Where did they go?

      In the latest episode of The Drivecast, we delve into the Baby Duramax (code-named LMK), discussing its potential, what it was meant to be, and the sole prototype that escaped destruction.

      If you have information about the LMK Baby Duramax, reach out to us at tips@thedrive.com.

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      **Full Transcript**

      Caleb: Okay, Joel. I'm excited to discuss this on a podcast finally. It consumed a lot of my time while I was digging into the story about the lost Duramax, and now here we are. It’s ironic since you just spent the past week in a Silverado EV Trail Boss. Quite a different vehicle, wouldn’t you agree?

      Joel: Absolutely. We're living in such a different world compared to 2008 and the LMK situation. I just had the Chevrolet Silverado EV Trail Boss, which is an electric truck with a massive battery, weighing quite a bit, with all this torque—775 pound-feet—and power—725 horsepower. It's on 35-inch tires and offers remarkable off-road capability. It’s like a walking contradiction. The timing is ironic as we talk about the Baby Duramax and what might have been, especially when considering how differently the truck segment could have developed, which we’ll explore. Before we jump in, Caleb, can you outline what happened and the history leading up to uncovering the engine that survived?

      Caleb: Sure thing. The 4.5-liter Duramax project ramped up in the mid-2000s, nearing its completion at the decade's end. It was intended to make waves in the half-ton truck market, which at the time was quite competitive among the Big Three—GM, Ram, and Ford. But looking back, the half-ton segment wasn’t particularly impressive. Perhaps I’m alone in that view, but Ford had the 5.4-liter Triton, which continues to receive its fair share of criticism. GM decided to think ahead and develop a diesel engine for their 1500-series trucks, aiming to outperform the small-block gas V8s. They set out to create an engine that could fit anywhere a small-block V8 could, hoping to deliver better fuel economy and 520 pound-feet of torque. They succeeded in developing this engine with a hot-V turbocharger, well before similar technologies appeared in sports cars like the Mercedes-AMG GT and the Cadillac CT6-V Blackwing. This was a landmark piece of engineering not just for its time in 2006-2007 but even today. That torque output remains unmatched by contemporary light-duty diesel engines. Unfortunately, by the time 2008 and 2009 rolled around, GM's Chapter 11 bankruptcy sidelined the project entirely. We only had stories about it; there were no firsthand accounts about performance until I interviewed observers like Gail Banks.

      Joel: Before we dive deeper into the engine, let’s clarify the scope of this. It’s not just about trucks, right? You mentioned that this engine would fit wherever