| name | used-car-advisor |
| description | Evaluate used car listings, estimate fair prices, and guide purchasing decisions. |
Used Car Advisor
Evaluate used car listings, estimate fair value, flag known-problem models, and coach negotiation.
When to Use
- "Find me the best [car] under $X" — search for real listings first, then evaluate
- Evaluating a specific listing or comparing options
- "Is this a fair price?" / "What's wrong with this model year?"
- Negotiation prep before contacting a dealer
When NOT to Use
- New car purchasing, repair diagnosis, insurance (use insurance-optimizer)
Listing Search Workflow
When a user asks to find a car, follow these steps in order:
Step 1: Search for real listings across multiple platforms. Use specific price, mileage, and location filters. Present actual listings with real prices — never lead with ballpark estimates.
Step 2: Collect and organize results. For each listing, capture: year/make/model/trim, price, mileage, location, dealer vs. private, and listing URL.
Step 3: Evaluate and compare. Apply the Fair Price Method (below) and flag any Known Problem Models or Red Flags.
Step 4: Provide pre-filtered search links so the user can browse themselves (e.g., cars.com/shopping/ferrari-california/price-under-80000/). Don't just link site homepages.
Research Sources (use webSearch/webFetch)
Inventory / Listing Search
| Source | Best for | Notes |
|---|
cargurus.com | Deal ratings, days-on-market | Shows "great/good/fair/overpriced" vs. market |
cars.com | Pre-filtered URLs by price/make | Supports URL filters like /price-under-80000/ |
autotrader.com | Broad dealer inventory | Good trim-level filtering |
edmunds.com | Listings + TMV pricing | Combines inventory with valuation |
autolist.com | Savings vs. market average | Aggregates from multiple sources |
| Facebook Marketplace | Private sellers | Often cheaper than dealers; search by region |
carsforsale.com | Broader dealer network | Good for less common models |
Bring a Trailer (bringatrailer.com) | Specialty/enthusiast/exotic cars | Auction format with sold-price history |
Hemmings (hemmings.com) | Classic and collector cars | Specialty listings |
DuPont Registry (dupontregistry.com) | Luxury and exotic cars | High-end inventory |
preowned.ferrari.com | CPO Ferraris | Factory-certified pre-owned |
Valuation & Reliability Research
| Need | Source | Query pattern |
|---|
| Recalls by VIN | nhtsa.gov/recalls | Fetch directly with 17-char VIN |
| Complaint clusters | carcomplaints.com | "[year] [model] problems site:carcomplaints.com" |
| Repair cost estimates | repairpal.com | "[model] [repair] cost repairpal" |
| Fair market value | KBB, Edmunds, cargurus.com (shows days-on-market + deal rating) | |
| TSBs (technical service bulletins) | nhtsa.gov or "[model] TSB [symptom]" | |
| Long-term reliability | dashboard-light.com, Consumer Reports (paywalled — search "consumer reports [model] reliability reddit" for summaries) | |
Known Problem Models — Flag These Immediately
When user mentions any of these, warn before discussing price:
| Avoid | Years | Issue | Failure cost |
|---|
| Ford Focus/Fiesta | 2011-2016 | PowerShift DCT — shudder, slip, class-action settled | $3-4k transmission |
| Nissan Altima/Sentra/Rogue/Pathfinder/Versa | 2013-2017 (worst) | Jatco CVT — overheats, limp mode, ~120k mi lifespan | $3.5-5k |
| Subaru (most) | 2012-2017 | CVT (warranty extended); also head gasket <2012 | $2-7k |
| BMW/Audi/Mercedes | Any out of warranty | Normal wear = premium parts/labor; depreciates 50%+ by yr 5 | Budget $2-3k/yr |
| Hyundai/Kia 2.0/2.4L Theta II | 2011-2019 | Rod bearing failure, engine seizure (recall) | Engine replacement |
| Chevy Cruze | 2011-2015 | Coolant leaks, turbo failure | $1-2k recurring |
CVT buying rule: Demand transmission fluid service records. No CVT service by 60k mi (4-cyl) or 80k mi (6-cyl) → walk away. Metal belt on metal pulleys — old fluid = cooked transmission.
Safe defaults: Toyota Corolla/Camry, Honda Civic/Accord (Honda's CVT is the exception — reliable), Mazda3/6, Lexus anything. Toyota Prius 2009-2020: 5/5 CR reliability every year.
Exotic & Luxury Cars — Different Rules Apply
Exotic and high-performance cars (Ferrari, Lamborghini, Porsche, McLaren, Aston Martin, Maserati, etc.) operate on completely different cost structures. Flag this immediately when a user asks about these brands.
| Item | Mainstream | Exotic/Luxury |
|---|
| Pre-purchase inspection | $100-200 | $300-500+ (specialist required) |
| Annual maintenance budget | $500-1,500 | $5,000-10,000+ |
| Transmission repair | $2-5K | $15-25K+ |
| Engine work | $3-8K | $15-50K+ |
| Brake job (all 4) | $300-800 | $3,000-8,000 (carbon ceramics: $15K+) |
| Tires | $400-800/set | $1,500-4,000/set |
Exotic car buying rules:
- Always use a marque specialist for PPI, not a general mechanic
- Search sold listings on Bring a Trailer for real transaction prices — asking prices on exotics are often negotiable by 10-20%
- Check brand-specific CPO programs (Ferrari Approved, Porsche CPO, Lamborghini Selezione) — CPO warranty can save tens of thousands
- Service history is everything. Incomplete records on an exotic = walk away
- Join model-specific forums (FerrariChat, Rennlist, Lamborghini-Talk) for ownership cost reality checks
Listing Red Flags
| Flag | What it means |
|---|
| Salvage/rebuilt/"clean rebuilt" title | Totaled once. Insurance may refuse comprehensive. -40% value |
| Price 20%+ below CarGurus "great deal" | Scam or undisclosed damage |
| "Runs great, just needs [X]" | If it were cheap to fix, they'd have fixed it |
| Odometer ends in 000 / round number | Possible rollback; cross-check Carfax mileage entries |
| No cold-start video on request | Hiding startup rattle (timing chain) or blue smoke (rings) |
| Dealer add-ons mandatory (nitrogen tires, VIN etching, "protection package") | Junk fees — refuse or walk |
Fair Price Method
- Pull KBB private-party + Edmunds TMV + 3 comparable CarGurus listings (same trim, ±15k miles, ±100 mi radius)
- Average them, then adjust: below-avg miles +5-10%, accident on Carfax -10-25%, one-owner +$500, new tires +$400-800
- Check days-on-market (CarGurus shows this). >45 days = dealer is motivated
- Subtract cost of any needed work (use RepairPal estimates)
Negotiation Playbook
Before contact:
- Get pre-approved financing from a credit union — removes dealer's biggest profit lever
- Find 2-3 competing listings for the same model. Screenshot them.
The ask:
- Email/text only until price is locked. Never negotiate on the lot.
- Ask for out-the-door (OTD) price — tax, title, doc fee, everything. "What's the OTD on stock #____?" Refuse to discuss monthly payments.
- Open at 10-15% below ask (dealer) or 15-20% (private). Anchor with KBB private-party number even at a dealer.
- After your offer: stop talking. First to fill silence loses.
Timing: Last 2-3 days of the month, weekday morning. Salespeople under quota will eat margin. (Caveat: if they already hit quota this does nothing.)
Trade-in: Get it appraised separately (CarMax/Carvana give free written offers). Never let them bundle trade-in value into the purchase — it obscures both numbers.
Before signing: Read every line of the buyer's order. Reject "market adjustment," "dealer prep," mandatory add-ons. Verify VIN on contract = VIN on door jamb.
Pre-Purchase Inspection — Non-Negotiable
$100-200 at an independent shop ($300-500 for exotics — use a marque specialist). NOT the seller's mechanic. Any seller who refuses → walk. Specifically request:
- Compression test (engine health) — all cylinders within 10% of each other
- Scan for stored/pending OBD codes (some sellers clear codes before showing)
- Lift inspection: frame rust, leaks, CV boot tears, uneven tire wear (alignment/suspension)
- Cold start — arrive before the seller warms it up. Listen for rattle (timing chain), watch for blue smoke (oil burning) or white smoke that lingers (head gasket)
Regional Search Strategy
Regional pricing differences can be significant — always search multiple regions:
| Region | Tends to be cheaper for | Watch out for |
|---|
| Midwest / South | Luxury & exotic cars (lower demand) | Hail damage (Midwest), flood titles (Gulf states) |
| Southwest (AZ, NV, NM) | Older cars (no rust) | Sun damage to paint/interior |
| Northeast / Rust Belt | Nothing specific | Frame rust, salt corrosion — get underbody inspection |
| Florida | High supply of luxury/exotic | Flood damage, hurricane salvage titles |
| California | High supply overall | Higher prices due to demand; emissions compliance |
Tip: Search nationwide first to establish fair market price, then narrow by region. A $5K price difference can justify shipping ($500-1,500 depending on distance).
Comparison Web App
After finding the best options, build a web app that displays a visual comparison page so the user can evaluate listings side-by-side.
Each listing card should show
- Car image — use the actual photo scraped from the listing URL. Never generate, synthesize, or use placeholder images. Only display real photos from the source listing. If no image can be scraped, show a text-only card instead.
- Year / Make / Model / Trim
- Price (with deal rating if available: great/good/fair/overpriced)
- Mileage
- Location (city, state, distance from user)
- Dealer vs. private seller
- Key flags (known problems, red flags, or positive signals like one-owner/no accidents)
- Direct link to the original listing
Layout
- Card grid or side-by-side layout, sortable by price, mileage, or deal rating
- Highlight the best-value picks visually (border, badge, or background color)
- Include a summary section at the top with the recommendation and why
Always generate the comparison page alongside the text-based analysis — the web app is a visual complement, not a replacement for the detailed evaluation.
Limitations
- Can't pull VIN history directly (user must buy Carfax/AutoCheck, ~$25-40)
- Regional price variance is real — rust-belt vs. southwest vs. PNW differ 10-15%
- Not a substitute for a physical PPI
