The 6.6L L8T is arguably the most overbuilt V8 engine General Motors currently puts in a pickup truck. It’s designed for durability first — big displacement, low-stress power delivery, and the kind of heavy-duty construction you expect in a 2500-class truck. That said, one of the most common comments I see about this engine is that it’s a gas guzzler. So instead of relying on assumptions or brochure talk, I put this Chevy 2500 HD through my real-world fuel economy loop to see what it actually re