The Physics and Economics of Moving 44 Tonnes at 56mph
Hacker News
February 23, 2026
AI-Generated Deep Dive Summary
The behavior of large trucks on highways, such as their slow speeds and seemingly inefficient overtaking maneuvers, is often misunderstood by drivers. These actions are not merely a result of driver inattentiveness but are dictated by a combination of EU regulations, engine limitations, and economic constraints. For instance, the 1992 EU directive mandates speed limiters on trucks over 12 tonnes, capping their highway speeds at 56 mph (90 km/h). This physical restriction, combined with weight limits and fuel efficiency concerns, shapes how trucks operate.
A fully loaded articulated truck weighs around 44 tonnes, which is nearly 30 times heavier than a typical family car. This massive weight has significant implications for fuel consumption, safety, and handling. Trucks consume about 10 times more fuel per mile compared to cars, with an average fuel burn rate of 30 liters per hour at highway speeds. These figures highlight why the trucking industry is obsessed with even minor improvements in efficiency—fuel costs alone can run over £50,000 annually for a single truck.
The physics of energy storage also poses a major challenge for alternative powertrains like electric or hydrogen trucks. A battery capable of matching the range and energy density of diesel would add significant weight, reducing payload capacity. For example, a battery pack storing equivalent energy to 400 liters of diesel would weigh around 16 tonnes, effectively eliminating that much cargo space. This makes electrification a complex issue, requiring not just technical advancements but also rethinking how freight is moved.
The economics and physics of trucking are closely intertwined, making it one of the most challenging sectors for innovation. The industry’s reliance on diesel is driven by its high energy density and affordability, which provides long range with minimal fuel weight. Transitioning to alternative powertrains would require not just new technology but also changes in how freight is transported, potentially increasing costs and reducing efficiency
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Originally published on Hacker News on 2/23/2026