eBay Motors, Guaranteed Fit

Against a Q1 baseline, returns dropped 9%, finder completion rose 12%, and gross merchandise bought grew 0.86%, roughly $60M a year in a category that brought in about $7B in the US. Fewer people bought a part that didn’t fit, and more people finished adding their vehicle instead of giving up partway.

eBay built Guaranteed Fit on this work and launched it in the US, Germany, and the UK. On its Q1 2023 earnings call, eBay credited “multiple quarters of product and fitment investments” for faster growth in Parts & Accessories. I received two Spot Awards for the work.

What I designed

Fitment

• Fitment badge system for fits, does not fit, and might fit
• The fits check mark across search, product pages, and checkout
• Finder modules for search, browse, and product pages

Vehicles and Garage

• One vehicle input with a VIN shortcut
• Garage for saved vehicles
• Finding tires by vehicle or by size

What I led

• Design of the fitment system behind Guaranteed Fit, from the Finder and My Garage to the fits check across search, product pages, checkout, and marketing
• Months of cross-functional alignment with Search, product grids, product pages, checkout, and the buy box to place fitment
• The case for keeping the fit mark a standard check mark, with design systems and design leadership, before the Guaranteed Fit program was built on it
• Covering my design manager's role during her sabbatical, while leading Finders and Tire Installation in parallel
• Carrying fitment further after launch, into the German checkout and the new two-column listing page

The opportunity

Buying parts for your car online is an act of faith. You’re trusting that the part will work with the vehicle you drive. eBay had fitment tools, but few people used them. They sat below price, reviews, and seller ratings, so people often picked a part before they knew if it fit. Entering a vehicle was its own hurdle. eBay’s Research team found that a lot of people don’t know their vehicle’s exact year, and plenty will guess rather than admit they’re not sure.

The goal was to help shoppers find parts that fit by getting more of them to use the Finder, and to get them to trust its answer. That would help sellers too, with fewer fitment questions and fewer returns. eBay was also investing in the data behind fitment, buying myFitment in 2022 to help sellers add accurate fitment.

I had spotted most of the places where trust broke down, and the Research team’s work confirmed them. People read vehicle entry as a filter for one search, not as saving their car. Being told a part partly fits confused them. And they wanted the fits message to come from eBay, not just the seller.

Product team vision deck, selected slides

View screens

Product team vision deck, selected slides

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Persona 1, the maintainer, an inexperienced shopper 01/04

Constraints

Engineering scoped the work as a reskin of the current Finders with small improvements. The requirements said the Finder shouldn’t be treated like a search filter, even though fitment works like one. Partner teams left very little space for us. There was no room in search, the buy box, or the cart, and no room for subheads or a second call to action. And because so few people used the Finder, product and I wanted it highly visible, even disruptive.

Small layout changes at eBay have historically affected purchasing numbers by millions, so teams protect their domains, and that instinct is right almost everywhere on the platform. My theory, however, was that car parts aren’t like shoes. A shoe can run a half size off. A part either fits or it doesn’t, and a part that doesn’t fit leaves the car broken while you wait for the next one, not to mention the return fees and shipping.

Making that case across functions and partners took months and landed with different teams at different times. Search came around first and became an advocate. Product grids, product pages, the buy box, and checkout took longer.

Fitment also sat on a category tree we didn’t control. The Motors tree had once run to about 1,500 categories and had been cleaned up the year before. Buying and selling shared that one taxonomy, and a separate project was building a curated category tree for sellers. My Garage and Find Parts That Fit sat at the very bottom of the tree, below every category, so the tools that tell you whether a part fits were the hardest to find.

Legacy taxonomy

Legacy Motors taxonomy

Fit

Decisions

On paper the work was a reskin of the Finders. But the problems reached past the Finder, into how fit was shown, how vehicles were saved, and where fitment showed up on the page. The decisions below take those on in that order. Each one had to look and act the same on iOS, Android, mobile web, and desktop, for cars, trucks, motorcycles, and tires, in the US, the UK, and Germany.

A state model, not a screen

The core of Guaranteed Fit is three states: the part fits, it doesn’t fit, or it might fit and needs more information. That’s standard across automotive commerce, and eBay’s backend already had a version of it. My job was making it show up consistently and honestly everywhere someone might be deciding on a part. The guarantee raised the stakes. If a part carried the check and didn’t fit, eBay paid for the return, so a false positive wasn’t just a bad experience; it was a bill.

Fitment states

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A check mark people already know

Getting everyone aligned on using a standard check mark for fitment took a lot of work across several teams, including design systems and design leadership. The mark itself is nothing new. Most fitment sites use a check, and that was my argument: it’s a convention shoppers already recognize, so eBay shouldn’t reinvent it.

Other versions kept coming up, like a blue shield with a check, or folding fit into eBay’s money-back guarantee icon. I held the line on the check. I made the same argument about the Finder itself, that it should work the way fitment works on other sites.

In a July 2023 leadership review, one piece of feedback put it plainly: “To Eric’s point, this is the industry standard, we’re doing something non standard.” Research backed it up: shoppers wanted the fits message to clearly come from eBay, and a familiar check read that way.

Once the mark was approved, the Guaranteed Fit program was built on top of it. The guarantee came after the icon, not before.

I also made the case that the same system could work well beyond car parts, anywhere one thing has to work with another: a camera and a lens, a printer and its ink, a lawnmower and its blade. The design system documented it that way: a filled confirmation check confirms when an item fits your vehicle, with a note that fitment could later expand to other categories, like fashion.

Confirmed fit

One vehicle input, saved to a garage

Before the redesign, the Finder looked and worked differently across eBay, and shoppers treated it as a filter for one search, even though most assumed eBay would remember their car. It didn’t. I redesigned it as one input that saves.

In the new Finder, year, make, model, and trim work for first-time buyers and experts alike, with a VIN shortcut for anyone who knows exactly what they drive. If a search already names part of a vehicle, the Finder starts from there, and asks a quick question first when “honda” could mean a car or a motorcycle. Entry adapts by market: a registration number in the UK, where many people don’t know their exact model year, and HSN/TSN numbers in Germany.

Once added, the vehicle stays in My Garage until you remove it and follows you across search, product pages, and checkout.

Friction on purpose

In product design, we usually want to remove friction from a user’s goal, like shopping in e-commerce. This was a case where the opposite was true, and adding friction on purpose solved a lot of the problem.

When you’re in a Motors category without a saved vehicle, we now ask you to add one and explain why it matters. If you don’t, we keep reminding you as you browse and buy. Each reminder makes it clearer that adding your vehicle will save you time, money, and frustration.

Even with the extra step, finder completion rose 12%.

We put the Finder at the top of search results and category pages, in both Parts & Accessories and Tires, and when you scroll it shrinks into a bar that stays at the top of the screen. Once you add a vehicle, it replaces the add vehicle prompt, and every part that fits shows the Fits your vehicle check.

On the product page, fitment leads the page and also shows in the buy box, and Change opens your saved vehicles. When an item doesn’t fit, a link offers to find parts that will. After launch, one-click Finders and a mini garage cut the steps further.

Shop tires by size or by vehicle

Sometimes it’s easier to find a tire by size than by vehicle, so you can switch and browse that way. While you browse by vehicle, the size (or both sizes when front and rear differ) and the rim size show with your match.

To help people enter all three numbers, I made a tire illustration for the size flow. It shows where each number sits on your own tire and fills in as you pick them: the width in millimeters, the aspect ratio as a share of that width, and the rim diameter.

Learnings

I was wrong about tooltips. I first proposed tooltips to explain the Finder on search, but at eBay people closed them right away without reading them. The ask had to be part of the page, not on top of it.

Making something better doesn’t always help. People build habits and workarounds around things we’d call bad UX, and fixing them means a new learning curve that, at eBay’s scale, can cost a lot of sales. That’s part of why the green check and a familiar Finder were worth the fight: shoppers already knew them. Changes need research, a look at the business impact, and a path people can follow.