I had Grok run the impact of diesel at $6 – $10 per gallon:

At a national average of about $5.90 per gallon, the U.S. is already at a record retail diesel price, with California near $7.80. Further increases would land hardest on freight, farming, construction, and food distribution rather than passenger cars.

Diesel is the fuel of trucks, tractors, many trains, and construction equipment. Fuel is typically 15–30% of the delivered cost of food and a large share of trucking operating costs. A common surcharge formula is (current diesel minus a contract base) divided by truck MPG; at 6–6.5 MPG, each extra $1 per gallon adds roughly $0.15–$0.17 per mile that shippers eventually pay. Demand for distillate has already fallen 6–10% year-over-year, showing some demand destruction is underway.

$6/gallon
This is only a small step from today’s national average. Incremental effects would be modest but poorly timed: the U.S. is entering peak harvest and pre-heating demand. Extra freight costs would mostly show up as higher fuel surcharges on existing contracts rather than an immediate nationwide price jump. Food and perishable goods would feel it first because they move frequently and often require refrigeration. The extra national fuel bill would be on the order of a few billion dollars a year before any further demand drop.

$7/gallon
That is about 18% above the current national average and already the reality in California. Trucking fuel surcharges would rise another ~$0.15–$0.17 per mile. Using industry rules of thumb (a 10% fuel-cost rise associated with 2–3% higher food prices), this level could add a few extra percentage points to grocery inflation over subsequent months as contracts reprice—especially produce, meat, and dairy. Farmers would face higher harvest costs on top of already elevated fertilizer and input prices. Construction and infrastructure projects would see higher equipment and materials-haul costs. Core goods inflation would tick higher; the Fed would have less room to treat it as a “temporary energy blip.”

$8/gallon
This would be ~35% above today’s national average and, in inflation-adjusted terms, in the range of or above the 2008 peak. Pass-through would be broader: more retailers and distributors would raise list prices rather than just add temporary surcharges. Independent truckers and smaller farms would face tighter margins or closures. Food-price pressure would compound because diesel hits both production (tractors, irrigation, harvest) and every subsequent truck movement. Expect stronger demand destruction, delayed or canceled shipments of bulky/low-value goods, and a noticeable drag on real household purchasing power. GDP effects from a shock of this size are typically estimated in tenths of a percent rather than a full percentage point in the modern, less energy-intensive U.S. economy, but the pain would be concentrated in logistics, agriculture, and lower-income households.

$9–$10/gallon
These levels would represent a severe, sustained energy shock. National extra fuel expenditure could approach $50–$55 billion per extra dollar before volume declines (roughly 55 billion gallons of distillate used annually at recent run-rates). Freight rates would reprice sharply; some lanes or small carriers would become uneconomic. Food inflation could run several extra percentage points on top of existing pressures. Construction activity would slow. The combination of higher input costs, weaker real incomes, and tighter financial conditions (if the Fed stays restrictive against rising core inflation) would raise recession risk. Effects would be highly uneven: West Coast prices would likely be $2+ above the national average, so $10 nationally could mean $12+ in California. Lower-income households would absorb a larger share of the burden through food and goods prices even if they never buy diesel themselves.

These are order-of-magnitude estimates, not forecasts. Actual outcomes depend on how long prices stay elevated, how completely costs are passed through versus absorbed in margins, how much further demand falls, and whether crude/refinery constraints ease. The 2026 shock has already produced measurable demand destruction and rising producer and consumer prices; each additional dollar from here would add another layer of that same transmission mechanism.