Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Sports Car Engines
The Ultimate Car Application that brings to you the roaring sounds of the fastest, most powerful sports cars from around the world!
$0.99 · In-app purchases
PRICE
$0.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
7 ratings · Top 15%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included17 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Sports Car Engines: map the core Sports workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Include more sounds for different engines.
Assumption to check: Limited engine sound variety
Validate with people who use this workflow before building.
Hypothesis 2
Add community features like reviews or comments.
Assumption to check: Lack of user interaction features
Validate with people who use this workflow before building.
Hypothesis 3
Implement a system for regular content updates.
Assumption to check: Inconsistent updates of engine data
Validate with people who use this workflow before building.
Hypothesis 4
Enhance the search with more filtering parameters like year or manufacturer.
Assumption to check: Limited filtering options
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
The Ultimate Car Application that brings to you the roaring sounds of the fastest, most powerful sports cars from around the world! √ THE NO.1 APP FOR SPORTS CAR ENGINE SOUNDS! Experience the thundering sounds of Ferraris, Porsches, Lamborghinis, BMWs, Mercedes, Chevrolets and many more! √ FEEL THE THRILL! Over 190 raging sports cars from 35 different manufacturers, including: - ALFA ROMEO: 8C Spider - GT - GTV - 159 - 156 GTA - 147 GTA - Spider - 4C - ARIEL: Atom - ASTON MARTIN: DB7 - DB9 - DBS - Vantage N24 - Vantage - Vantage RS - Vanquish - One-77 - Rapide - Virage - AUDI: RS6 - RS5 - RS4 - R10 - R8 V10 - R8 - S8 - S5 - TTRS - Sport Quattro One - RS3 - RS7 - BENTLEY: Continental GT - Azure T - Mulsanne - Flying Spur - BMW: M6 - M5 - M3 - X6 - X5 - 650i - 850i - Z4 - Z8 - 130i - M4 - BUGATTI: Veyron - Veyron Super Sport - T35 - CHEVROLET: Corvette C6 - Camaro SS - Cobolt SS - Corvette L82 - Camaro Z28 - Nova SS - DODGE: Viper GTS - Charger RT - Charger SRT8 - Challenger - Dart - Avenger - FERRARI: Enzo - 458 Italia - 599 GTB Fiorano - 599XX - California - F430 Scuderia - 612 Scaglietti - 360 Modena - 575M Maranello - F50 - F40 - F355 Spider - 348 Spider - Testarossa - FF - P4/5 Competizione - F12 Berlinetta - FORD: GT - Mustang Shelby GT500 - Mustang Shelby GT500 Elanor - Mustang Boss 302 - Mustang - Mustang Mach 1 - Focus RS - Escort XR3i - Mustang GT - HOLDEN: Monaro VXR - HSV Clubsport R8 - HSV GTS - HONDA: NSX - S2000 - Civic Type-R - CRX - JAGUAR: XFR - XKR - XJ220 - S-Type R - X-Type - XJR - Jaguar F-Type VS 8 - KOENIGSEGG: CCGT - CCXR - Agera - LAMBORGHINI - Reventon - Aventador LP 700-4 - Gallardo - Murcielago - Diablo - Countach - Huracan LP 610-4 - Sesto Elemento - LEXUS: LFA - IS-F - SC430 - LOTUS: Exige - Evora - Elise - MASERATI: Quattroporte - Granturismo - MC12 - Ghibli - MCLAREN: F1 - MP4-12C - MERCEDES: SLR 722 - S65 AMG - CL65 AMG - CLK63 AMG Black Series - E63 AMG - C63 AMG - SL55 AMG - SLK55 AMG - R63 AMG - SLS AMG - CLS63 AMG - CLA45 AMG - MITSUBISHI: Lancer Evolution X - 3000GT - Eclipse - NISSAN: Skyline GTR R-35 - Skyline GTR R-34 - 370Z - 350Z - Silvia S15 - 240SX S13 - 300ZX Twin Turbo - PAGANI: Zonda C12S - Zonda F - Huayra - PORSCHE: Carrera GT - Cayenna Turbo - Panamera S - Panamera Turbo - 911 Carrera 4S - 911 Turbo S - GT3 RS - Cayman S - Boxster - 996 - 956 - 930 Turbo - 911 SC - 356 - 918 Spyder - Macan Turbo - SALEEN: S7 - SSC: Ultimate Aero - SUBARU: Impreza WRX STi - Impreza STi - BRZ - TOYOTA: Supra - Celica - GT86 - TVR: Cerbera - Chimaera - Griffith - Tamora - T350 - Tuscan - VOLKSWAGEN: Phaeton W12 - Touareg W12 - Golf R32 - Passat CC - Beetle RSi - Scirocco TSi REVIEWS: - 5/5 - Listening to the actual engine will send the adrenaline flowing through your veins and your hearts tachometer will be red lining for sure! Sports Car Engines is a car lover’s dream!" - The iPhone App Review - 5/5 - Beauty meets beast with this great app for car lovers!” - App Shouter - 5/5 - Sports Car Engines has got fantastic sounds of the best sports cars from around the world!” - iPhone Footprint
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
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BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
