Case Study — Google Ads
Engines.Transmissions.1.74 million leads.
Seven years of auto parts Google Ads behind a network of used engine and transmission lead sites — five million dollars of managed spend, and a cost per lead that never moved.
The Client
A network, not a website
Our client doesn’t sell used engines and transmissions from one storefront. He sells them from a network of lead sites — separate brands, separate domains, each pointed at a slightly different slice of the same enormous market: the driver whose engine just died and who needs a price today.
Maintain Digital runs paid search across every site in that network, and designed and built two of the sites themselves — including the flagship. Not a campaign, not a channel test: the entire demand engine for a business whose phone only rings when we make it ring.
The Portfolio
The sites we feed
Each brand runs its own account, budget and keyword architecture — so they compete with the market instead of with each other.
Sir Car PartDesigned & built by us
911,336Leads $2.93Cost / leadQuality Engines & Transmissions
589,907Leads $2.72Cost / leadMetallo Delivers
193,233Leads $2.99Cost / leadAM Used Auto Parts
43,386Leads $3.21Cost / leadNationwide Engine SupplyDesigned & built by us
1,092Leads $5.60Cost / leadThe Challenge
A market where cents decide
Used auto parts is a volume business with thin margins and brutal competition. Every one of these searches is contested by salvage yards, national aggregators and marketplaces with budgets that dwarf a single operator’s. Nobody wins it on brand. It gets won on cost per lead, and the margin for error is measured in cents.
The trap in this vertical is that cheap leads are easy at low spend. Take a small budget, run it on the tightest, highest‑intent keywords, and post a great number. The moment you scale — more keywords, broader match, more geography — efficiency collapses and cost per lead runs away from you.
Our mandate was the hard version of the job: grow the volume without losing the number.
The Work
How we run auto parts Google Ads
One account per brand
Every site gets its own account, budget and keyword architecture. Brands in the same network bidding on the same terms would inflate their own auction — separation keeps them competing outward, not inward.
Part, make, model, year
Search demand here is a matrix, not a list. Campaigns are built around how people actually search for a specific part for a specific vehicle, with continuous negative keyword work stripping out the wrecking‑yard and DIY‑repair traffic that never converts.
Tracking that is actually correct
Bidding algorithms are only as good as the signal underneath them. We own the tracking layer across the network and we audit it. On the newest site we found the account reporting zero conversions while it was producing thirteen leads a day — and fixed the chain end to end.
The landing page is part of the media buy
A quote form that loads slowly, or breaks, is a media problem. We designed and built both the network’s flagship and its newest site specifically to convert paid traffic — quote form above the fold, on the page the click lands on, no navigation detour between intent and submission.
Seven Years of Compounding
The results
Every figure below comes straight out of Google Ads, across all five active accounts, for the period January 1, 2020 through September 9, 2026. Nothing is modelled and nothing is projected.
Volume went up and up
All five accounts combined
2026 is a partial year — January 1 to September 9 — shown pale.
Budget scaled as the engine proved out
Annual managed spend across the network.
Seven years. Spend up 4.3×. Cost per lead never left a 59¢ band.
In the year we scaled hardest — 2024, at $1.21M spent and 460,000 leads — cost per lead came in at $2.64, the lowest of the entire seven‑year run, and below where the network started on a fifth of the budget. The 2026 figure reflects two accounts still in their learning phase.
Where the leads came from
Source: Google Ads, all campaigns across five accounts, January 1, 2020 – September 9, 2026. “Leads” are primary conversion actions — lead‑form completions recorded on the thank‑you page, plus tracked phone calls — counted per completion rather than per unique visitor. Cost per lead is total spend divided by total leads for the period shown. 2026 figures are year‑to‑date through September 9 and are not annualised.
Anybody can buy cheap leads on a small budget. The test is what happens when you put four times the money through the same machine — and the number holds.
Let’s Talk
What’s your number?
If your cost per lead climbs every time you raise the budget, the problem usually isn’t the budget.