One Rooftop, Two Websites: How Splitting a GM Dealership Online Splits Its AI Visibility

Many GM dealers sell more than one brand under one roof: Chevrolet and Buick GMC, or Buick GMC and Cadillac. A lot of them run a separate website for each brand. We wanted to know what that does to their visibility in AI search.

The answer is clear. At these stores, one website gets almost all the AI citations. The second website is usually invisible. And two websites don't add up to more reach than one.

This post builds on our OEM Deep Dive, which found that GM stores AI cites are the ones that already rank in Google.

Methodology

• Sample: the same 4,846 GM dealer websites from our OEM Deep Dive, pulled from GM's dealer locator on Oct. 19, 2026.

• Rooftops: GM's locator lists each brand at a location separately, with its own website. We grouped websites that GM lists at the same location. The 4,846 websites belong to 3,864 rooftops.

• Data source: Ahrefs, October 2026. AI citations from six engines (Google AI Overviews, AI Mode, Gemini, Perplexity, Microsoft Copilot and ChatGPT), plus ranking keywords and estimated organic traffic for each website.

• Strongest site: at rooftops with more than one website, the site with the most AI Overview citations. The others are "second sites."

Finding #1: Nearly One in Four GM Rooftops Runs More Than One Website

Of the 3,864 GM rooftops we studied, 896 run two or three websites. That's 23% of rooftops, and their 1,878 websites make up 39% of all GM dealer websites.

The second site is usually the smaller brand. Most strongest sites are Chevrolet. Most second sites are GMC, Buick GMC or Cadillac.

What this means for you: If your store runs more than one website, you're not alone. About four in 10 GM dealer websites share a roof with another one.

Finding #2: One Site Takes Almost Everything

At rooftops with more than one website, the strongest site holds 84% of the rooftop's AI Overview citations. The second sites split the other 16%.

68% of second sites have no AI Overview citations at all. More than half rank for fewer than 10 searches.

The strongest site at a multi-site rooftop is cited in AI Overviews as often as a single-site store, 75% of the time. But it ranks for fewer searches (30 for the typical strongest site, vs. 45 for a single-site store) and earns less traffic (about 231 monthly visits vs. 394).

What this means for you: If you run a second brand website, check whether AI search knows it exists. For most GM stores in this position, it doesn't.

Finding #3: Two Websites Don't Add Up to More Reach

You might expect two websites to reach more shoppers than one. They don't.

Add up every website at a multi-site rooftop, and the typical store ranks for about the same number of searches as a store with one website. It earns a little less traffic, and it's cited in AI Overviews just as often.

In other words, the second website mostly divides the same search reach. It doesn't add new reach.

What this means for you: A second website isn't a second chance to be found. It's a second site to keep ranking, and most stores aren't getting value from it in AI search.

Finding #4: Buick GMC Sites Have the Most to Lose

The gap shows up for every GM brand, but it's widest for Buick and GMC.

A Buick GMC website at a stand-alone Buick GMC store is cited 78% of the time. A Buick GMC website that shares a roof with another brand's site is cited 33% of the time.

Among second sites, Buick GMC fares worst. Only 22% of Buick GMC second sites are cited in AI Overviews, and the typical one ranks for six searches. Cadillac second sites do better, at 55%.

What this means for you: If you run Buick GMC on its own website next to a Chevrolet or Cadillac site, that Buick GMC site is the one most likely to be missing from AI answers.

What We Are Not Claiming

A few limits, stated plainly.

• Correlation, not a controlled test. Stores that run separate brand sites may differ in other ways, including market size and how much they invest in each site.

• We didn't test merging sites. Combining websites has its own search risks, and this data doesn't tell you what would happen if you did it.

• Rooftops come from GM's locator. We grouped websites GM lists at the same location. A few stores may be grouped differently in real life.

• AI results move. This is a snapshot from October 2026.

The through-line holds. AI search rewards the website that ranks, and at most multi-site GM stores, only one website does.

Where This Leaves Your Store

If your rooftop runs more than one website, start with three questions. Which of your sites does AI search cite? How many searches does each one rank for? And is the second site earning its keep, or splitting attention your main site could use?

A Search-to-Sale Audit shows what shoppers find when they search for your store, your brands and your models across Google, AI search and local results, site by site.

Book a Search-to-Sale Audit