Picture a customer who already decided to buy from you. She saw your inventory last week, told her husband, and planned to come in Saturday. On Friday, she sees a retargeting ad from your store on Facebook. On Saturday, she buys. Now ask yourself a hard question. Did that ad sell the car, or did it just wave at a customer who was already walking through the door? Your retargeting vendor will happily count that sale. The truth is that vendor added nothing.
The credit-grab problem
Certain vendors are built to claim customers who were always going to buy. Retargeting is the classic example. It shows ads to people who already visited your site, which means it aims at your warmest shoppers by design. Brand-search vendors do the same thing. They bid on your dealership’s name, then take credit when someone who was searching for you clicks the ad instead of the organic link right below it. In both cases the vendor intercepts demand you already created and bills you for it as if it were new.
Think about how that plays out on your own lot. A shopper spends twenty minutes on your VDPs, favorites three trucks, and comes back the next day on his phone. Of course he sees your retargeting ad. He is on your site constantly. The ad is not creating that interest, it is following it. A vendor that shows warm ads to warm shoppers will always produce a report that looks impressive, because the audience was already sold before the first impression ran.
Attribution is not the same as incrementality
This is the distinction that separates real marketing from expensive theater. Attribution asks which touchpoint got credit for a sale. Incrementality asks a better question. Would this sale have happened anyway, without the ad? A touchpoint can be fully attributed and completely non-incremental. The customer touched it, so it gets credit, but it changed nothing about the outcome. When a vendor shows you an attribution report, they are showing you which sales they touched. They are not showing you which sales they caused. Those are very different numbers, and only one of them is worth paying for.
Here is a concrete way to feel the gap. Say your brand-search vendor reports forty sales last month from people who searched your dealership name. Those buyers typed your name into Google on purpose. They were coming to you. If you paused that campaign, most of them would still click the organic result sitting right underneath the ad and walk in anyway. The vendor attributed forty sales. The number it actually caused might be four. You are paying full price for a report that counts your own reputation as the vendor’s work.
How to test whether a vendor actually adds sales
You do not have to take anyone’s word for it. You can test incrementality directly:
- Run a holdout. Turn the vendor off in one market or for a set period and watch what happens to sales. If nothing drops, you have your answer.
- Geo-test. Keep the vendor running in some zip codes and pause it in comparable ones. Compare sales between the two groups.
- Check the overlap. Ask how many of the vendor’s claimed sales also appear in your other channels. Heavy overlap means they are claiming shared credit for demand others created.
- Watch the brand-search trap. If a vendor is bidding on your own name, test pausing it. Often the organic result captures those same buyers for free.
A simple version works even without fancy tools. Pick two similar weeks and two similar zip codes. Run the vendor in one, pause it in the other, and read cost per car sold across both. If the paused market sold the same number of cars, the vendor was riding demand you already owned.
What honest vendors do differently
A vendor confident in its own value will welcome a holdout test. It knows the sales will drop when it turns off, and it wants you to see that drop. A vendor that resists testing, that insists its attribution report is proof enough, is telling you something without meaning to. If the only evidence a vendor can offer is credit it assigned to itself, you are not measuring performance. You are reading a marketing document the vendor wrote about the vendor.
Pay for lift, not for luck
Every dollar you spend on non-incremental marketing is a dollar you could have kept. Those customers were coming anyway. The goal is not to reward vendors for standing near your sales. The goal is to find the marketing that actually creates buyers who would not have shown up otherwise, and to fund that. When you measure incrementality instead of accepting attribution, you stop paying vendors to take credit for your own success.
Frequently asked questions
Is retargeting always a waste of money?
No. Retargeting can bring back a shopper who genuinely drifted away, and some stores run it profitably. The problem is not the tactic, it is grading it on attribution instead of lift. Run a holdout on your retargeting for a few weeks. If sales hold steady, you were paying to reach buyers who were already yours. If sales dip, you found real incremental value worth keeping.
How long does a holdout test need to run?
Long enough to cover your normal sales cycle, which for most dealers means at least three to four weeks, and longer for slower-moving inventory. Pause too briefly and you only measure the shoppers already deep in the funnel. Give it a full cycle so you capture the buyers who would have started fresh during that window.
What if a vendor refuses to be tested?
Treat that refusal as data. A vendor that truly drives incremental sales wants you to see the drop when it turns off, because that drop is its best sales pitch. A vendor that will only point at its own dashboard is protecting a number it cannot defend any other way.
These are the numbers you should own, not rent from a vendor. See how VCTRS helps dealers hold every vendor accountable on our vendor accountability page.