I was reading the NASA truck aerodynamics thread earlier and realised that commercial freight is one of those fields that touches everyone's daily life (everything you own arrived on a truck) but sits in a complete knowledge blindspot for most people.

I work in fleet fuel efficiency and wrote up the foundational mental model, covering why trucks weigh what they weigh, why they're all doing exactly 56mph, why diesel is so hard to replace, and why 1% fuel savings matters when you're burning 43,000 litres a year.

This is the first in a series, there's already a 2-part deep dive on hydrogen up as well. Tried to keep it accessible without dumbing it down.