CarGurus Mobile Finance Calculator
CONTEXT
Prototyped a finance calculator to predict out-the-door pricing
For my senior capstone, I collaborated with the CarGurus product team to explore and design new on the lot mobile features for 45M+ monthly buyers.
CarGurus is the #1 most visited automotive shopping site in the U.S. However, the company’s mobile app was rarely used at dealerships so myself along with three other Tufts human factors engineering students set out to design new mobile features. We wireframed multiple ideas and I created our final finance calculator prototype using Lovable.
In late 2025 CarGurus introduced Dealership Mode, a new bottom navigation tab that includes a finance calculator
A variation of our finance calculator was shipped to 45M+ monthly users!!
83% of user testers would recommend the finance calculator to a friend
4.3/5 average ease of use score from user testing on final prototype
Old: generic and simple
New: detailed and customizable
PROBLEM
Buyers rarely used the CG mobile app at dealerships and often felt anxious during negotiations
On the business side, less than 10% of users opened the CarGurus app while at dealerships. As for buyers, 80% reported being stressed out by hidden fees and unclear pricing while only 9.7% felt confident they got the best deal. Existing calculators failed to estimate the true ‘out-the-door’ cost.
GOAL
Design a new CG mobile app feature that empowers buyers at dealerships
Based on CarGurus internal research and conversations with recent buyers, we decided to focus on improving information transparency surrounding financing and hidden fees. We also had to ensure our solution didn’t jeapordize dealers’ relationships with CarGurus.
How might we improve the CarGurus app experience on the lot without jeopardizing CG's relationship with dealerships?
SOLUTION
We created a new finance calculator to prepare buyers for negotiations
The final prototype gives buyers a clear breakdown of all costs, simplifies financing steps, and serves as a meaningful resource for negotiations. I led the design direction across five iterations and built the final mobile prototype with Lovable.
Final prototype under NDA. See what shipped.
01 - Finance Info & Goal Setting
Input your personal finance info
Buyers begin by confirming or editing prefilled finance details and setting a target monthly payment. Personalized suggestions guide users toward meeting their goals.
- Prefilled finance info from prequalification or manually entered
- Set a monthly payment goal and receive instant suggestions to meet it
- Experiment with different inputs to see how they affect total and monthly cost
02 - Cost Breakdown
Anticipate hidden costs and add-ons
As users scroll, the calculator transitions into a receipt-style breakdown of taxes, fees, and add-ons. Optional dealer incentives and trade-ins dynamically adjust total costs.
- View every fee, add-on, and tax clearly listed in one organized view
- Add trade-ins or discounts at the dealership to reflect real-time negotiations
- Build trust with dealers and reduce stress during the buying process
03 - Estimate Summary
Feel confident on-the-lot
The final section mirrors the financing calculations from a buyer’s order form, giving users a realistic estimate before entering negotiations.
- Save and share estimates with clear total cost and payment
- Compare saved estimates to explore different financing options
- Reduce decision fatigue and arrive to the dealership with confidence
PROCESS
Research
Users rarely used the CarGurus app on-the-lot and were frustrated with hidden costs
Internal research showed the app was seldom used at dealerships, while secondary research and 5 buyer interviews revealed struggles with hidden fees and unclear financing terms. These findings highlighted cost and information transparency as a gap to address.
“Between the taxes, fees, and dealer add-ons, I had no idea what the real price was. I wish there was a way to see it all clearly without having to ask a million questions”
– Car Buyer Interviewee
Onsite research revealed that confusing paperwork overwhelmed buyers
We visited 3 dealerships, interviewed 5 dealers, and observed buyers struggling with financing paperwork. Buyer's order sheets scattered key information across multiple boxes, leaving buyers unsure if they were getting a fair deal.
Information transparency became the clear problem to solve
After consolidating 9 buyer interviews, 5 dealer interviews, and multiple on-the-lot observations, we mapped the entire car buying process. Buyers often lost confidence at each step, eroding trust in dealers and leading to stressful decision-making.
Prototypes
We explored 9 concepts to uncover the most promising directions
Our team brainstormed and sketched 9 potential solutions, from feature comparison tools to AR visualization. This exploration allowed us to consider a full range of potential directions before committing to one solution.
Three concepts showed the most promise
By informally testing with buyers and pitching to CarGurus, we discovered which concepts resonated with users. We mapped our findings onto an impact vs effort analysis and selected 3 concepts to build out in Figma.
1. QR Codes
Generate and scan QR codes to share info and save cars
2. Finance Calculator
Estimate out-the-door price with full cost breakdown
3. Deal-O-Meter
Show vehicle price range by area with good/fair/bad rating
4. Live Car Availability
Live updates on vehicle price and availability
5. Feature Comparison
Rank and compare feature packages to preferences
6. Appointment Booking
Book dealer visits and share financial info upfront
7. Car Buying Vocab
Tap on key terms for simple popup explanations
8. Car Comparing
View cars side-by-side to compare features and price
9. AR Visualization
Visualize cars and add-ons in real spaces
User testing showed the Finance Calculator was most effective
I built low-fi interactive flows in Figma and tested them with 6 participants. Feedback showed the Finance Calculator gave buyers the greatest clarity and confidence, so we chose it as the key feature to prototype.
Deal-O-Meter
Finance Calculator
Estimate Summary
Design
New iterations added key features that addressed user needs
I led the design for the Finance Calculator, frequently testing with participants and refining the visual design to address user needs. Through feedback, I added features like a sticky finance banner, a monthly payment goal, and options to save or share estimates.
I brought the Finance Calculator to life with a Lovable prototype
Our Figma prototype conveyed the core flow, but complex interactions and live calculations weren't possible. At CarGurus' suggestion, I built the final prototype in Lovable, which brought the design to life with real functionality and gave me hands-on experience with AI-assisted design tools.
83%
Would recommend to a friend
(user testing with prototype)
4.3 / 5
Ease of getting a monthly estimate
(task-based usability test)
1
Mobile finance solution
(built by CarGurus)