Values from real sales
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BB · Type 01 · The InstrumentBuild sheet Nº 0001 · Oct 2026

Every car
has a number.

We read the listing, pull the real sales, and tell you where to stop.

Free on the Chrome Web StoreAdd to ChromeiPhone appComing soon to the App Store
137146155165174184193202212 BID BAND × $1,000
050100150200250 BID TARGET × $1,000
$177,000
051015202530 COMPS SALES USED LOW NORMAL TIGHT

Car value reportWhat's it really worth?

Or turn the dials with a saved report

Preview: these are real, saved BidBetter reports of finished auctions. Live reports start at launch.

Vehicle
2023 Porsche 718 Cayman GT4 RS Weissach
Mileage
6,000 mi
Gearbox
automatic
Listing
Bring a Trailer ↗
Band
$168,000–$186,000
Hammer
$175,000
Nº 02 · The data

Not a guess.
Real sales.

AI chats guess. BidBetter checks real sales.

Regular AI chat

It guesses.

No real sales behind the number.

Its answer · 2023 718 GT4 RS

$150k–$220k?

“Somewhere around there, depending on condition.”

  • Guesses from memory
  • Can't see what sold last week
  • Sounds just as sure when it's wrong

BidBetter

It checks real sales.

Priced from 400,000 real sales, updated every 15 minutes, plus a daily morning market read.

Bid target · 2023 718 GT4 RS

$177,000

From 21 real sales · it sold for $175,000

  • One clear number to bid to
  • Built from cars that actually sold
  • Every sale shown, so you can check
Real auction results
400,000+
Completed collector-car auctions since 2018, with what each car actually brought.
Fresh sales, all day
15 min
New results land in BidBetter sales data every 15 minutes. Last weekend's sale counts.
Morning market read
Daily
Every morning we read the market: which cars are bidding strong, and which are cooling.

Same car, two answers. The AI answer is an illustration; the BidBetter report is a real saved report of a finished auction. Value a car →

Nº 03 · 46 seconds

See it work.

Share a link on the iPhone, read the same car in the Chrome extension, paste it on the web. No edits, no speed-up.

A 1986 Porsche 911 Turbo auction listing beside the BidBetter panel: bid target $160,000 from 17 comparable sales.
iPhone shareChrome extensionWebRecorded live, unedited
Nº 04

How it reads

Three steps. No opinions, no asking prices. Just completed sales of the same car.

  1. 1

    Read the listing

    Paste a link, add photos or type the details. We work out the exact car: year, trim, mileage, gearbox.

  2. 2

    Find real sales

    We pull completed sales of the same car and adjust each one to this car's mileage, spec and date.

  3. 3

    Get your Bid target

    One number to bid to, the range it should land in, and every sale behind it.

Sample report2023 Porsche 718 Cayman GT4 RS Weissach6,000 mi · Bring a Trailer

Bid target

$177,000

Tight confidence

Likely range
$168,000 – $186,000
Full range
$159,000 – $196,000
Comparable sales
21 real sales
Walk away above
$196,000

Sales behind it · 5 of 21 shown

  • 2025 Porsche 718 Cayman GT4 RS Weissach - 118 MilesSotheby's Motorsport · Aug 7, 2026$209,821adjusted −5.0%
  • 2023 Porsche 718 Cayman GT4 RS WeissachBring a Trailer · Aug 3, 2026$198,000adjusted −1.5%
  • 2023 Porsche 718 Cayman GT4 RS Weissach - 177 MilesSotheby's Motorsport · Jul 23, 2026$166,964adjusted +5.1%
  • 2024 Porsche 718 Cayman GT4 RS Weissach - 125 MilesSotheby's Motorsport · Jul 8, 2026$166,071adjusted −0.1%
  • 2025 Porsche 718 Cayman GT4 RS Weissach PackageCars & Bids · Jun 8, 2026$197,000adjusted −9.4%

21 comparable sales; adjusted for mileage, specification and sale recency.

Track record

Real reports

Back-tested BidBetter reports of finished auctions, priced only from sales that closed before each auction ended. Bid target against what the car actually sold for. Open any card for the full report.

Each report used only sales that closed before that auction ended. Mean miss across these 4: 1.67%. These are selected examples, not every report, and past results don't guarantee future ones. Bid targets are estimates, not appraisals.

Nº 05

Where it works

One account. Three places to read a car.

EXT
bringatrailer.com/listing/2023-porsche-718-cayman-gt4-rs-79
BidBetter
VALUES FROM REAL SALES
ListingValue a CarGarage
2023 PORSCHE 718 CAYMAN GT4 RS WEISSACH · 6K MI
BID TARGET
$177,000
LIKELY $168k–$186k● TIGHT
WALK-AWAY$196,000
WITH FEE$203,500
SALES USED · 21
2025 Porsche 718 Cayman GT4 RS Weissach - 118 MilesSotheby's Motorsport · Aug 7, 2026$209,821
2023 Porsche 718 Cayman GT4 RS WeissachBring a Trailer · Aug 3, 2026$198,000
2023 Porsche 718 Cayman GT4 RS Weissach - 177 MilesSotheby's Motorsport · Jul 23, 2026$166,964

Nº 04.1

Chrome extension

Open the listing, open the side panel. Bring a Trailer, Cars & Bids, PCARMARKET and more.

Free on the Chrome Web StoreAdd to Chrome
iOS
9:41
Shared from bringatrailer.com
2023 Porsche 718 Cayman GT4 RS Weissach
6k mi · automatic
BID TARGET
$177,000
$168kTIGHT$186k
FROM 21 SALES
Bring a Trailer 10Sotheby's Motorsport 5PCARMARKET 4Cars & Bids 2
Save to garage

Nº 04.2

iPhone app

Share a link from any app. The number comes back in seconds.

iPhone appComing soon to the App Store
DESK
BidBetter DESK
ReportsGarageShare linksAccount
Saved reports4
CarTargetBandConf.
2023 Porsche 718 Cayman GT4 RS WeissachBring a Trailer · ended Sep 3, 2026$177,000$168k–$186kTIGHT
2020 Porsche 911 Carrera 4S CoupeBring a Trailer · ended Sep 16, 2026$119,000$113k–$125kTIGHT
1960 Porsche 356B CoupeBring a Trailer · ended Sep 25, 2026$71,000$67k–$75kNORMAL
2016 Porsche Cayman GT4Bring a Trailer · ended Sep 30, 2026$128,000$122k–$134kNORMAL

Nº 04.3

The desk

Your saved reports, garage and share links, in one place.

On the web, free accountOpen the desk →
Nº 06

Plans

Pick a gear. See plans.

Contact us about the API → Priced per account, by agreement. Web and extension only; never sold in the iPhone app.

Questions

FAQ

Short answers. More on the FAQ page.

What does a report cost?

Free is $0: 3 reports a month, 5 once your email is verified. Pro is $49.99/mo for 1,000 reports a month and Dealer is $199/mo for 5,000; both renew automatically every month until you cancel online. The API is priced per account, so contact us for a quote. See plans.

Where does the data come from?

A database of 400,000 real auction results, updated every 15 minutes, plus a daily morning market read.

Can I cancel anytime?

Yes. Cancel from your account in the billing portal. Paid access runs to the end of the period you paid for, then you are back on Free.

How do Dealer wholesale values work?

Wholesale values are for licensed dealers. When you choose Dealer, we verify your dealer license before wholesale values turn on.