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CarParts.com: Achieving 3.2x revenue efficiency and unlocking the true value of Paid Social through full-funnel measurement
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CarParts.com, a leading online retailer of auto parts and accessories, has been a pioneer in eCommerce since launching its website in 1999. As the marketing landscape evolved - more platforms, more complexity, more privacy changes - so too did their need for a modern approach to measurement.
The Challenge
CarParts.com had ambitious growth targets and knew that diversifying their channel mix - and capturing the true value of upper-funnel investment - was key to reaching them. But their existing measurement stack was holding them back.
Relying on Last Click attribution created a structural bias toward demand capture channels, systematically under-crediting the channels that create demand in the first place. Meta and TikTok were being credited with a fraction of the revenue they were actually driving - making it difficult to justify scaling investment in either channel.
The team also faced growing misalignment between what platform reporting and GA4 were telling them. Without a single reconciled view that marketing and finance could trust, it was difficult to make the case for investing in higher-funnel channels - and harder still to know where the real incremental opportunity sat.
The Solution
CarParts.com onboarded with Fospha in January 2025. From day one, they had access to two years of modelled performance data - giving them a long-range view of how every channel contributed to growth. Fospha's modelling also fully integrated with their custom eCommerce platform, something no other provider had been able to do.
At the core of Fospha is a full-funnel MMM, built to quantify the impact of every impression, view, and click - from top-of-funnel awareness through to bottom-funnel conversions - measured at the ad level and updated daily. Unlike black-box platforms that ask teams to trust without understanding, Fospha's glass-box approach means every output can be interrogated by marketing, finance, and leadership alike.
Fospha’s measurement revealed what Last Click had been hiding: Paid Social was driving 24% of total revenue while accounting for just 8% of total spend - a 3.2x revenue-to-spend efficiency ratio that had been invisible until now. Armed with a trusted, daily view of true channel performance, CarParts.com had the confidence to act.
The Results:
Using Fospha data to make their marketing decisions, CarParts.com’s Paid Social revenue grew 32% YoY while spend increased just 20% more, demonstrating that a data-driven approach to Paid Social, powered by Fospha’s always-on measurement, enables brands to confidently allocate budget to high-performing channels that Last Click attribution would otherwise overlook.
Paid Social’s share of total paid revenue grew from 16% to 24% YoY, with Meta’s contribution scaling significantly and TikTok’s efficiency improving markedly - a compounding return on a measurement system that updates every day.
Scaling Meta
Armed with Fospha’s signals, CarParts.com more than doubled their Meta investment over the 8-week period YoY, resulting in an 83% Meta revenue uplift. Conversions grew 75% YoY and new customer conversions increased 60%, proving that scaled Meta investment, guided by accurate measurement, can deliver transformative top-line growth.
For CarParts.com, one of Fospha’s most underrated benefits was internal. With conflicting signals from GA4, Meta, and their own platform data, justifying budget decisions to leadership was a recurring challenge. Fospha provided a single, reconciled view that marketing and finance could interrogate together, making it easier to move budget up the funnel and defend those decisions with confidence.
Scaling TikTok
CarParts.com more than doubled their TikTok investment, and revenue followed - growing 100%. Conversions grew 91% and new customer conversions were up 84%. TikTok's share of total business revenue grew from 6.9% to 8.8% over the period - each dollar of spend generating nearly 3x its share in revenue.
For CarParts.com, one of Fospha's most underrated benefits was internal. With conflicting signals from GA4, Meta, and their own platform data, justifying budget decisions to leadership was a recurring challenge. Fospha provided a single, reconciled view that marketing and finance could interrogate together - making it easier to move budget up the funnel and defend those decisions with confidence.
"For a long time, we knew there were channels we were underinvesting in - we just couldn't prove it internally. Fospha's forecasting changed that. Beam showed us exactly where our next dollar would work hardest, and gave us the confidence to act on it. The revenue impact speaks for itself." – Christina Bylin, Head of Marketing, CarParts.com
The Bottom Line
CarParts.com achieved profitable growth by moving beyond Last Click and investing in channels that create demand - not just capture it. Fospha's always-on Digital Measurement OS gave the team the daily, granular, trusted data they needed to make that shift with conviction.
Fospha didn't replace experiments - it made them work harder. By ingesting live CLS results and using them to continuously calibrate the model, every test compounded rather than sitting in a slide deck. Episodic validation became a continuously improving system.
Measurement became insight. Insight became action. Action became growth. For CarParts.com, that foundation translated directly into revenue - and into a measurement system built to scale profitably in a world that moves faster every day.
