New findings from the 2026 Urban Science Harris Poll Study* validate the importance of advertising in the automotive shopping journey. When buyers were asked if they noticed car ads when browsing online, 93% of surveyed auto buyers indicated they did, and of those, 46% said those ads were somewhat or extremely influential.

Auto buyers are paying attention to online advertising. At the same time, they are now more likely to cross-shop brands and dealerships. Almost half (44%) of auto buyers reported spending more time researching before contacting a dealer compared with one year ago. Meanwhile, 31% said they now prioritize value and price over brand loyalty.

A less linear path to purchase introduces new challenges for automotive advertisers. The more fragmented the shopping journey, the greater chance ads will reach the wrong audiences at the wrong time, which in turn, makes it harder for marketers to understand how their media investments are performing. As a result, wasted ad spend can quietly accumulate across channels.

Why is Wasted Automotive Ad Spend on the Rise?

Wasted automotive ad spend can stem from multiple factors. Since most vehicle purchases occur offline, it can be difficult to connect media exposures to validated sales outcomes. If automotive marketers aren’t leveraging sales truth to target in-market shoppers and suppress those who have already purchased, they may be reaching buyers after they convert or targeting consumers who were never in market in the first place.

Ad fraud is another challenge. In unauthenticated environments, ad fraud can dilute media efficiency by routing ads toward bots rather than qualified shoppers. Regardless of the cause of wasted ad spend, the scale of the problem is significant. The Association of National Advertisers (ANA) estimated advertisers incurred $26.8 billion in wasted ad spend in Q2 of 2025 through their programmatic media buying.

While incrementality studies can’t eliminate the sources of wasted ad spend, they can help bring them to light. Incrementality testing acts as a diagnostic tool to identify wasted spend and optimize away from it. Through small, controlled experiments, incrementality tests compare different audience groups or campaign conditions to evaluate the causal impact of media.

For instance, a simple incrementality test might compare results between an audience exposed to ads and an unexposed control group. For automotive marketers, this provides the foundation for causal measurement. By linking media to people-based, authenticated sales data, marketers can determine whether their campaigns contributed to actions consumers wouldn’t have taken otherwise.

To consistently measure those outcomes, automotive marketers need sales truth: a decisioning layer tying media activity to verified offline vehicle sales. By pairing incrementality testing with daily industry sales data, advertisers can isolate the impact of specific campaigns and tactics, identify which investments are contributing to outcomes and continually optimize real results.

Using Native Tools to Support Incrementality Studies

Incrementality testing may sound complicated, but it can actually be very simple, and many platforms already support controlled experimentation within their native environments. For example, Meta’s A/B testing feature allows advertisers to compare the performance of test and control groups against a specific outcome. Advertisers might serve ads to one audience while withholding ads from a comparable control group, using sales-based outcome data to assess whether the exposed group outperformed the baseline. From there, they can extend and refine their experiments to determine the point at which ad exposures begin to deliver diminishing returns.

Urban Science’s collaboration with Meta to support Mazda Motors of North America on its “More to Move You” campaign demonstrates how incrementality testing can work in practice. Mazda collaborated with Urban Science to securely send daily offline sales data to Meta, using the Conversions API for offline events. This surfaced verified sales signals directly within Meta’s native decisioning environment, enabling the platform to auto-optimize toward both online engagement and in-store sales. Then, using Meta’s native conversion lift testing, Mazda measured performance against a holdout audience to isolate incremental sales outcomes.

  • When compared with Mazda’s standard campaign approach, “More to Move You” achieved a 3.5X return on ad spend and a 64% lower cost per incremental sale.

How Can Automotive Advertisers Build an Incrementality Testing Cadence?

Incrementality studies are a practical way to assess media efficiency and realign spend with the strongest areas of opportunity. Advertisers can begin with small, simple experiments and scale over time. To start building an incrementality testing cadence, automotive advertisers should:

  1. Define the most important business outcome, such as sales or qualified leads.
  2. Select one journey stage to test: for instance, awareness, consideration or conquest.
  3. Build a control and treatment plan using a holdout audience or geographic or time-based test.
  4. Set a measurement window based on the audience’s typical purchase cycle.
  5. Monitor the test for diminishing returns by tracking frequency, overlap and saturation.
  6. Reallocate spend to the segments and channels showing incremental lift.
  7. Repeat the process quarterly to maintain an ongoing testing cadence.

Even when marketers aren’t sure if their campaigns are driving results, many still worry “going dark” will lead to losing share of voice. This fear can lead automotive advertisers to pour more ad dollars into their campaigns even as confidence in their results erodes.

A science-driven approach brings greater clarity to today’s fragmented auto-buyer journey. By combining incrementality testing with daily industry sales data, automotive advertisers can ground their campaigns in sales truth. With this foundation in place, they can optimize toward validated sales outcomes, curb wasted spend and invest more in the areas where advertising is truly driving impact.

Connect with Urban Science to learn how you can pair daily industry sales data with incrementality testing to identify wasted ad spend and optimize your media budget.

*This survey was conducted online by The Harris Poll on behalf of Urban Science among 3,012 U.S. adults aged 18+ who currently own or lease or plan to purchase or lease a new or used vehicle in the next 12 months (between January 5 to January 28, 2026) and among 252 U.S. OEM automotive dealers, whose titles were Sales Manager, General Manager or Principal/VP/Owner (between January 5 to February 4, 2026).

 

Summary

The auto-buying journey is becoming less linear and more fragmented, making it harder for automotive advertisers to recognize and reduce wasted ad spend. By combining incrementality testing with daily, verified vehicle sales data, automotive marketers can isolate campaign impact, determine which media investments are driving outcomes and direct spend toward the areas delivering results.

FAQ

  • What is incrementality testing in automotive advertising? Incrementality testing is a diagnostic tool to evaluate the causal impact of media. Through controlled experiments (or incrementality studies), automotive marketers can compare different audience groups or campaign conditions to identify which campaigns, tactics, audiences and channels are contributing to outcomes.
  • Why is wasted ad spend a problem in automotive marketing? Wasted ad spend is a problem in automotive marketing because most vehicle purchases occur offline, making it difficult for advertisers to measure campaign performance and connect media exposures to validated sales outcomes. Unless they ground their campaigns in daily industry sales data, automotive marketers may be reaching buyers after they convert or targeting consumers who were never in market in the first place. In unauthenticated environments, ad fraud can also dilute media efficiency by routing ads toward bots.
  • How can automotive advertisers reduce wasted ad spend? Automotive advertisers can reduce wasted ad spend by combining daily industry sales data with incrementality testing to identify which investments are contributing to verified sales outcomes. With this clarity, advertisers can shift budget toward the media investments driving results and away from underperforming.
  • Why are incrementality studies important for automotive marketers? Incrementality studies are important for automotive marketers because most vehicle purchases occur offline, which makes it difficult to connect media exposures to validated sales outcomes. By pairing incrementality studies with daily sales data, automotive marketers can identify which media investments are driving sales and optimize toward the campaigns and tactics contributing to real-world outcomes.
  • What is sales truth? アーバンサイエンスの sales truth is the only decisioning layer allowing automotive marketers and AdTech platforms to connect media investment to daily verified vehicle sales outcomes. As the foundation for Urban Science’s Media Performance suite, sales truth transforms daily, verified vehicle buyers into outcome-guided signals to improve planning, targeting, suppression and optimization.
  • How does daily, verified vehicle sales data support incrementality testing? For automotive marketers, daily, verified vehicle sales data is the causal measurement foundation for incrementality testing. When powered by daily industry sales data, incrementality testing gives marketers a reliable way to diagnose when and where their media dollars stop influencing sales and reallocate spend toward the channels, campaigns and tactics driving real outcomes. Over time, those same sales signals can feed back into advertising platforms to support experimentation, improve optimization and inform future media decisions.
  • Are incrementality testing features available within platforms like Meta? Yes, many media platforms support incrementality testing within their native environments. For example, Meta’s A/B testing feature allows advertisers to compare the performance of test and control groups against a specific outcome.
  • How can automotive marketers get started with incrementality testing? Automotive advertisers looking to get started with incrementality testing can begin with small, simple experiments using native incrementality testing features, such as Meta’s A/B testing or conversion lift tools. Alternatively, they can work with a partner to design and facilitate more advanced incrementality studies.