How AI Search Is Recommending Used Car Retailers: Monthly Trends

Executive Summary

CarMax still leads valid recommendation coverage at 35.9%, with Carvana in second at 32.8%. Over the three-month tracked window, both brands recorded declines beyond normal variation: CarMax fell 5.6 points from 41.5% in July 2026, and Carvana fell 5.5 points from 38.3% in July 2026. The gap between first and second now stands at 3.1 points, down from 3.8 points in August 2026 (37.6% versus 33.8%) and from 3.2 points in July 2026 (41.5% versus 38.3%). The narrowing gap reflects CarMax's cumulative decline rather than any recovery from Carvana.

The strongest upward mover over the baseline-to-current window was Group 1 Automotive, whose valid recommendation coverage rose 2.7 points from 2.5% in July 2026 to 5.2% in September 2026, a movement beyond normal variation across the tracked window. This net figure masks a sharper mid-series spike: Group 1 Automotive reached 7.2% in August 2026 before settling back to 5.2%. The sharpest cumulative decliner was Hertz Car Sales, down 8.6 points from 11.5% to 2.9% over the same window, with the August-to-September drop of 4.0 points itself beyond normal month-to-month variation. CarMax, Carvana, Enterprise Car Sales, and Hertz Car Sales all qualify as significant decliners across the series, while Group 1 Automotive is the sole significant riser.

Compared with August 2026, most brands' rates moved only modestly. Hertz Car Sales' 4.0-point decline to 2.9% is the one month-over-month move that exceeded normal variation, extending its two-month decline streak. AutoNation eased 3.9 points to 21.7% and Enterprise Car Sales eased 2.5 points to 5.0%, both within the range of normal month-to-month variation despite the raw shift. EchoPark (Sonic Automotive) moved the other direction, rising 1.4 points to 8.8%; the brand has now moved from trailing Hertz Car Sales by 3.4 points in July 2026 to leading Hertz Car Sales by 5.9 points in September 2026.

Each monthly run begins with 800 prompt-surface observations (496 unique questions in July 2026, 516 in August 2026, and 514 in September 2026) across the benchmark's defined AI/search surface universe. All 800 prompts in each month mentioned a tracked brand or competitor; 778 were relevant and 22 irrelevant in July 2026, 784 relevant and 16 irrelevant in August 2026, and 776 relevant and 24 irrelevant in September 2026. The public metrics use the 593 qualified observations from July 2026, the 598 qualified observations from August 2026, and the 576 qualified observations from September 2026 that survive both qualification stages.

Key Findings

Benchmark Context

The report separates the raw collection universe from the qualified analysis set. Brand-level recommendation percentages are calculated within the qualified benchmark set.

Benchmark-Level Metrics

Across the window, the qualified observation count contracted from July to September while the mix of answer shapes shifted, with August 2026 in between at 598 qualified observations.

The recommendation-shaped answer share fell from 36.4% in July 2026 to 30.9% in September 2026, with August 2026 in between at 30.4%. The valid recommendation shortlist share moved from 40.5% to 39.6% over the same window, having peaked at 42.5% in August 2026. The benchmark cannot distinguish platform behavior from measurement effects behind these shifts.

AI Recommendation Trend

The top two spots remain held by CarMax and Carvana, but both posted declines beyond normal variation across the tracked window while the middle of the field reordered around Hertz Car Sales' fall

Rankings shown are by valid recommendation coverage within the qualified benchmark set. CarMax, Carvana, Enterprise Car Sales, and Hertz Car Sales moved beyond normal variation across the tracked window, as did Group 1 Automotive on the upside. The rest of the category's movement came from smaller, individually stable shifts, including declines at AutoNation and DriveTime that did not cross that threshold.

What Changed This Month

CarMax

CarMax's valid recommendation coverage fell 5.6 points from 41.5% in July 2026 to 35.9% in September 2026, a decline that exceeds normal variation across the tracked window and marks a second consecutive month of decline. The August 2026 figure sat at 37.6%, meaning the August-to-September drop was a more modest 1.7 points.

The brand's rank-one rate slipped 1.5 points from 16.9% to 15.4%, with 89 rank-one recommendations in the September 2026 qualified set versus 100 in July 2026. Raw mention presence fell 4.6 points from 67.1% to 62.5%.

The distinction to notice: CarMax lost overall recommendation coverage across the window while its presence and top-of-list placement moved in the same direction, a broader pattern than a single weak signal. The brand remains the category leader, but the cumulative decline is now beyond normal variation across the window.

Highest-priority diagnostic: Which prompt types shifted away from CarMax across the three months, and did any single competitor consistently absorb those recommendations?

Carvana

Carvana's valid recommendation coverage fell 5.5 points from 38.3% in July 2026 to 32.8% in September 2026, a decline beyond normal variation across the tracked window. The brand has now declined in each of the two consecutive tracked months, from 38.3% to 33.8% to 32.8%.

Raw mention presence also fell, from 55.6% to 49.6%, a movement of 6.0 points. The rank-one rate moved down 0.9 points from 14.3% to 13.4%, with 77 rank-one recommendations in September 2026 versus 85 in July 2026.

The distinction the reader should notice is that both presence and recommendation coverage moved down together for Carvana across the window. This is a broader pattern than the leader's decline alone.

Highest-priority diagnostic: Which surfaces and prompt styles are associated with the presence decline, and which competitor absorbed the vacated recommendation positions?

Hertz Car Sales

Hertz Car Sales was the sharpest cumulative decliner, with valid recommendation coverage down 8.6 points from 11.5% in July 2026 to 2.9% in September 2026, a movement beyond normal variation across the tracked window. The August-to-September drop of 4.0 points was itself beyond normal month-to-month variation, taking the brand from 6.9% to 2.9%.

Raw mention presence also fell, from 13.2% to 4.9%, a movement of 8.3 points. The brand recorded just 17 valid recommendations in September 2026 versus 68 in July 2026, and raw mentions fell from 78 to 28.

The distinction to notice is that the brand's decline spans both presence and coverage, with the remaining recommendations holding slightly stronger positions: the top-three rate rose from 1.7% to 2.3% even as coverage fell sharply. Fewer shortlist appearances overall, but the ones that remain land with marginally better placement.

Highest-priority diagnostic: Which competitor absorbed the shortlist positions and raw mentions Hertz Car Sales lost, and what distinguishes the prompts where Hertz still appears?

Group 1 Automotive

Group 1 Automotive was the sole significant riser over the window, with valid recommendation coverage up 2.7 points from 2.5% in July 2026 to 5.2% in September 2026, a movement beyond normal variation across the tracked window. The path was not linear: the brand peaked at 7.2% in August 2026 before settling back to 5.2%, a 2.0-point drop from the prior month.

Raw mention presence rose 4.6 points, from 36.9% to 41.5%. The brand still records zero rank-one and zero top-three recommendations in September 2026, with 30 valid recommendations in the qualified set.

The distinction the reader should notice: Group 1 Automotive gained meaningful shortlist presence without converting it into top-ranked or even top-three answers. This remains a breadth gain without a prominence gain.

Highest-priority diagnostic: What drove the mid-series peak in Group 1 Automotive's coverage during August 2026, and why did part of that gain fade by September?

Enterprise Car Sales

Enterprise Car Sales declined 4.8 points from 9.8% in July 2026 to 5.0% in September 2026, a movement beyond normal variation across the tracked window. The brand has now declined in each tracked month, from 9.8% to 7.5% to 5.0%.

Raw mention presence also fell, from 10.1% to 6.9%, a movement of 3.2 points. Valid recommendations fell from 58 in July 2026 to 29 in September 2026.

The distinction to notice: Enterprise Car Sales lost both presence and coverage, but its sentiment remained the strongest in the category at 0.9, and the rank-one rate actually rose from 0.3% to 0.5%. The brand is being mentioned and recommended less often, yet the mentions that remain skew positive.

Highest-priority diagnostic: Which competitor absorbed the prompts that Enterprise Car Sales previously won?

EchoPark (Sonic Automotive)

EchoPark (Sonic Automotive) was one of the few risers in September 2026, with valid recommendation coverage up 0.7 points from 8.1% in July 2026 to 8.8% in September 2026, a stable movement that nonetheless moves the brand into fifth place. The August-to-September gain was 1.4 points, from 7.4% to 8.8%.

Valid recommendations rose from 48 in July 2026 to 51 in September 2026, and raw mention presence edged up from 19.6% to 20.3%. The rank-one rate rose from 0.3% to 0.7%, with 4 rank-one recommendations in September 2026 versus 2 in July 2026.

The distinction to notice: EchoPark gained ground while several of its mid-field competitors declined, moving the brand from the sixth-through-ninth cluster into a clear fifth place. The brand has also passed Hertz Car Sales over the window, moving from trailing it by 3.4 points in July 2026 to leading it by 5.9 points in September 2026.

Highest-priority diagnostic: Which prompts and surfaces are associated with the sustained recommendation presence, and is the gain concentrated in a narrow set of queries?

Buyer-Intent Interpretation

In July 2026, August 2026, and September 2026, all qualified observations fell into the Brand Recommendation class. The benchmark therefore measures which retailers AI systems choose when a shopper asks for a recommendation, and it cannot yet answer how AI frames pricing, value, or head-to-head comparison questions in this category. Price sensitivity, financing perception, and direct competitive matchups remain open questions that the current public benchmark does not reach.

Brand Opportunity Summary

The benchmark identifies where attention is warranted across the tracked field; a company-level analysis is needed to explain why each movement occurred.

Evidence Behind the Benchmark

The aggregate metrics are built from prompt-level observations (query, surface, recommendation outcome, rank, sentiment, and citations where exposed). Company-level analysis can go deeper into prompt, competitor, surface, and evidence patterns. Source presence is not automatically treated as proof of causation.

About This Benchmark

This report is part of the LLM Authority Index AI Market Discovery research program.

• AI Industry Market Discovery Methodology
• AI Industry Market Discovery Metrics
• AI Industry Market Discovery Standards

Report-Specific Interpretation Notes

• Small-count movements: Several brands operate on small valid-recommendation counts (DriveTime at 24, Hertz Car Sales at 17, Enterprise Car Sales at 29, Group 1 Automotive at 30 in September 2026). Their percentage movements rest on fewer observations and should be read with that context.
• Qualified denominator: All percentages are calculated within the qualified set of 593 (July 2026) and 576 (September 2026) observations, not the 800 raw prompts collected.
• Movement analysis: Month-over-month movement identifies changes worth investigating. It does not by itself establish the cause of those changes.

Next Step

The Public Benchmark Shows Where a Brand Is Winning or Losing. A Company-Level Audit Shows Why.

The aggregate percentages in this report raise questions they cannot answer: which high-intent prompts does each brand actually win, which competitor takes the recommendation when a brand loses, what attributes do AI systems associate with each option, and which external sources shape those answers? A brand that appears stable could be winning and losing in different prompt segments that cancel out in the monthly average. A brand like Hertz Car Sales, down 8.6 points, requires prompt-level inspection to understand whether the loss is concentrated in specific query types or spread across the surface universe.

A company-specific AI visibility audit maps those prompt, surface, competitor, ranking, sentiment, and evidence-source patterns into a prioritized visibility strategy. Where the benchmark shows movement, the audit shows the mechanism.

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