What will the SAAR of total U.S. light-vehicle sales be for December 2026?

The December 2026 U.S. light-vehicle SAAR is estimated at a median of 16.35 million units under continued Fed rate hikes, and 16.05 million units if the Fed pauses or cuts. The SAAR has been firmly established in the 16.2-16.8 million band through late summer 2026 fred.stlouisfed.org. Primary affordability markers, notably the record $812 average monthly payment and average transaction prices above $50,000 3 sources, are completely integrated into the baseline constraints. In both scenarios, the distributions are strongly right-skewed because of the asymmetric upside risk of a late-year buying surge ahead of potential January 2027 tariffs, consistent with the unconditional December baseline.

Standard pass-through processing confirms negligible direct short-term impact from a 25-50bp federal funds move. Auto loan rates track intermediate Treasuries and captive-finance subvention rather than the overnight rate, resulting in historically slow transmission 2 sources. A quarter-point hike translates to less than a $6 monthly variance on an $812 payment. Adjusting New York Fed elasticity estimates 2 sources for this partial pass-through over a strict three-month horizon directly caps the mechanical drag near 0.1 million units.

Continued Hikes Scenario: A decision to raise the upper bound above 4.00% by December 31 acts as a proxy for structural economic resilience. A hiking Fed is endogenous to firm growth, resilient consumption, and stable nominal incomes corporate.vanguard.com. These strong macroeconomic fundamentals effectively neutralize the marginal financing drag, anchoring the median at 16.35 million units. The 10th and 25th percentiles are 15.9 million and 16.15 million units, while the potential pre-tariff buying surge lifts the 75th and 90th percentiles to 17.4 million and 17.9 million units.

Pause or Cut Scenario: A departure from the modal hiking path lowers the median to 16.05 million units and introduces severe left-tail risk. An off-consensus pause or cut by December bypasses standard disinflationary benefits and instead signals acute labor market deterioration or a macroeconomic demand scare. This shift functionally replaces minor rate-driven affordability friction with a fundamental contraction in vehicle demand, pushing the 10th and 25th percentiles down to 15.0 million and 15.6 million units. The same asymmetric risk of a late-year buying surge ahead of potential January 2027 tariffs nevertheless raises the 75th and 90th percentiles to 17.0 million and 17.65 million units.