Dealerships have upped the ante when it comes to advertising used vehicles.

According to Fullpath’s April 2026 Auto Intelligence Index, new-vehicle inventory advertising is still the largest share of dealership ad spending, but investment in used and certified pre-owned vehicles took a giant leap forward last month.

The data, derived from Fullpath’s customer data platform and AI analytics across OEMs and its nationwide network of franchise dealerships, showed CPO ad spend soared 69% from the previous year, while used-inventory spend climbed 27.8%.

In addition, investment in fixed ops jumped 57.4% and “dealer near me” campaigns rose 23.4%. Meanwhile, spend on trade-in campaigns dropped 17% year-over-year to $207,000, which Fullpath said suggests dealers are shifting their acquisition focus toward inventory marketing rather than active trade solicitation.

Overall, the index found digital marketing’s return on investment also jumped in April, with dealership conversions rising 37.3% year-over-year in April and cost per lead dropping 14.8% to its lowest point in a year.

The company said that relationship illustrates “a new era of ad spend efficiency,” with dealerships increasingly relying on artificial intelligence automation to optimize their budgets and moving their spend toward the most favorable inventory and service channels.

“The April Fullpath Auto Intelligence Index results confirm we are entering a new era of ‘high-velocity’ automotive retail,” CEO and co-founder Aharon Horwitz said. “As average days’ supply tightens, the margin for error in digital spend has disappeared. Dealers are winning not by simply spending more, but by spending smarter and launching intelligent campaigns with the power of AI.”

Google’s search ad campaigns accounting for 64% of dealerships’ total digital ad investment, Fullpath said, as search continues to lead as the most cost-efficient high-volume channel at about $28.50 per lead.

But the report noted April ad spend on Google’s Performance Max grew 47% year-over-year, and PMAX conversions more than doubled, up 119%, with cost of while cost per lead lowered by 33%.

The index found a 10% rise in website traffic and identified a “six-message threshold,” showing the conversion likelihood increases six times when car shoppers send their sixth message to an AI chatbot, raising the probability of a sale to 45.6%, which Fullpath said shows “modern shoppers prioritize information depth over a quick hand-off.”