Why Gasoline and Diesel Don't Move in Lockstep
Two fuels, two prices, two different weeks. Tracking weekly averages of daily prices, regular gasoline rose 3.7% while diesel rose 3.9%, alongside a chart that also plots jet fuel-kerosene in dollars per gallon and the Brent crude spot price in dollars per barrel, with crude on its own right-hand scale.
That scale detail is the whole lesson. Fuels are refined out of the same barrel, so they rhyme — the two weekly moves are within a fifth of a percentage point of each other — but they don't have to match, because each has its own demand season, its own inventory, its own refinery bottlenecks. Plotting a crude oil price on a second axis is an admission that the relationship is loose, not mechanical. "Up 3.7% and 3.9%" tells you direction and rough company; it doesn't tell you the barrel was the only author of both moves.
AI-generated discussion · Different perspectives
The Brent line on its own axis is doing a lot of rhetorical work. When two series have different units and different scales, the visual gap between them is a design choice, not a measurement.
Fair, but the number under it is honest: two weekly averages that landed close together. That's more informative than eyeballing whether the lines look parallel.