Parts-and-service gross margin measures how much of an auto retailer's parts-and-service revenue remains after the direct costs assigned to that business.
Parts-and-service gross margin = parts-and-service gross profit ÷ parts-and-service revenue × 100%
If a dealer reports $700 million of parts-and-service revenue and $385 million of gross profit, the margin is 55%.
The remaining 45% represents direct costs included in cost of sales. Corporate SG&A and other operating costs still sit below gross profit.
Why aftersales matters
Dealers may call this business parts and service, fixed operations, customer care, or aftersales. It can include customer-pay maintenance and repairs, warranty work, collision repair, parts sales, internal reconditioning, and related services.
Vehicle sales are high-revenue transactions, but aftersales can contribute a disproportionate share of dealership gross profit. It may also behave differently from vehicle sales when consumers delay replacing cars but still need maintenance.
Lithia describes aftersales as an important customer-retention and profitability engine. AutoNation, Penske, and Group 1 separately disclose parts-and-service economics.
Margin and gross-profit dollars answer different questions
A dealer can grow parts-and-service gross profit while margin falls if revenue expands quickly enough.
Likewise, margin can improve while total gross profit declines if service volume weakens.
Use both:
parts-and-service gross profit = revenue × gross margin
This separates activity from profitability per revenue dollar.
What can move the margin
The margin can shift with labor pricing, technician wages, parts costs, warranty versus customer-pay mix, collision mix, internal reconditioning work, acquisitions, and accounting classification.
A dealer with a large collision business can have a different margin structure from one focused on maintenance and mechanical repair.
Same-store analysis can be cleaner
Acquisitions are common among public dealership groups. Consolidated service revenue can rise because the company bought stores.
Same-store revenue and gross profit help isolate organic performance. Penske, for example, reports same-store service-and-parts revenue and gross profit alongside consolidated results.
Gross margin is not operating margin
A 55% parts-and-service gross margin does not mean the dealer earns a 55% operating margin on service work.
Selling, general, administrative, occupancy, and corporate expenses remain below gross profit. For company-level efficiency, read aftersales margin together with SG&A as a Percentage of Gross Profit.
Primary-source examples
- Group 1 Automotive second-quarter 2026 earnings release
- Penske Automotive Group first-quarter 2026 earnings release
- Lithia Motors second-quarter 2026 Form 10-Q
Parts-and-service gross margin shows the profitability of the recurring aftersales engine behind the more cyclical vehicle-sales business.
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