Changelog

New: the Build Lab The Build Lab generates a complete build for a class. You choose your car, the target class and your discipline (touge, grip, track, drift, gymkhana or drag). The tool picks the parts, slider steps, gearbox and suspension that get closest to the class maximum score without going over. - Engine: automatic (the stock one, otherwise the lightest that holds the class), the lightest possible among all swaps, or a specific engine of your choice. - Options: fuel, tyre compound and, for drag, the target race. - The lightest car that stays in the class, with the weight split as close to 50/50 as possible. - Gearbox calculated for your discipline: ratios run up to the redline, and 1st gear is set for the launch. - The build is saved in one click and opens on its page, with every part and every value to set in game. The Build Lab is included in Premium+. Without Premium+, each account can create one build with the Build Lab: it is saved as soon as it is generated, and you cannot create a second one. Check your car, class and discipline before clicking. New: the page of a Build Lab build - The parts sheet is at the top of the page. It lists every part to fit and, for slots where the Build Lab proposes nothing, says "Leave stock". The tyre compound is listed too. - The settings to copy in game come right after the sheet. Fuel, input values, top speed and sharing move below. - New sections give values the page did not show yet: aero and weight reduction, brakes and tyres, extra gearbox settings (reverse gear, shift time). Front and rear suspension travel is added to the suspension settings. - The Build Lab values are the build's reference. If you change one (Premium+), it is marked as edited, and "back to the calculated value" returns it to the Build Lab value. Changed: the AI assistant goes to 200 questions per month Premium+ members can ask the assistant 200 questions per month, up from 60. Changed: the Premium page The Premium page has been redone: each feature is shown with a screenshot, and the plan comparison table includes the Build Lab. Changed: your build list - Each card shows its discipline in large type on the banner, and a "Build Lab" badge for builds created with the Build Lab. - If you have more builds than the free account limit, the counter says so clearly, and the limit banner offers to go Premium. - Premium members saw "(unlimited, admin)" next to their counter. Fixed: "(unlimited)". Changed: mobile - The feedback button no longer floats over the content on mobile: it is in the menu. - On the home page, the top menu no longer overflows the screen on phones or overlaps the logo on tablets. Fixed - The "Limit reached" message appeared twice when you clicked "New build" with 10 builds. - The menu close button stayed in French in the other languages.

Thanks to the players who tested setups in detail and sent us their measurements: this version comes straight from their feedback. New: two gear spacing options On the Transmission step, you now choose how your gearbox is spaced. - Standard: the current behaviour. Your gearbox ratios are kept, only the final drive is adjusted to reach your top speed. - Close ratios: the return of the previous calculation, requested by several of you. 2nd gear is set so you exit your slowest corner at the bottom of the powerband, and the following gears tighten up to top speed. Low gears are shorter and pull harder out of corners. Best on twisty touge roads. With close ratios, enter your exit speed from your slowest corner (70 km/h if left empty). Every ratio stays within the in-game slider range. Standard stays the default, and your existing builds don't change. No effect in drag. New: the values you entered, shown on every build A build page now shows all the car data used for the calculation: engine (power, rev limiter, torque, turbo, fuel, dyno peaks), chassis (weight, balance, center of mass, track widths), tires (sizes and grip), aero (Cx, Sx, downforce) and gearbox. On a shared build they appear at the very top, so anyone discovering your build knows where the settings come from and can reproduce the same setup with the same values. Changed: softer suspension in touge and track Testers found the track settings too nervous: the car wouldn't hold its line in long fast corners and drifted wide. In touge and track, the suspension now follows their recipe: - Softer springs: 30% softer at the front and 15% softer at the rear than the previous touge setting. - Dampers: the touge ones. Soft springs shift weight quickly and keep the tires in contact over bumps, and the dampers control that weight shift. Touge and track now share the same suspension base. Changed: softer anti-roll bars In grip, touge and track, the tool suggested anti-roll bars up to 6 to 8 times stiffer than the stock bar. They did almost all the work against body roll and the springs almost none: the car could lift a wheel over a bump taken under load. The bars now have a maximum share of the roll stiffness, by discipline: - Track: 65%. Smooth circuits, the car stays precise in fast corners. - Grip: 60%. - Touge: 55%. Bumpy roads, the springs need room to work. - Gymkhana: 55%. A bit of roll helps you feel the weight transfer. - Drift and drag: no change. Suggested bars usually land between 1.4 and 2.5 times the stock bar, never below it. The roll value shown is now the real roll of your setup. These caps are tuning choices, not measurements: if your car feels too soft in roll, stiffen the bars step by step. Changed: less camber and slight front toe-in For every discipline except drift: - Suggested camber is reduced by 30%. The car is more stable and more precise, and holds its line better in every corner. - The front goes from slight toe-out to slight toe-in (+0.05). Corner entry is smoother: the car follows the line instead of resisting and then diving to the apex. Changed: differential preload cut in half It locked each axle too much and made it hard to place the car off throttle and back on it. It goes from 0.4 to 0.2 times peak engine torque, for every discipline except drift, which keeps its value. The rear lock can rise slightly (+0.04 at most), because it takes the new anti-roll bars into account. Fixed: dyno screenshot upload - iPhone photos (HEIC), screenshots from some Android phones (AVIF) and GIFs were rejected with "unsupported format". They are now read. - Your screenshot is converted automatically before upload: file name, format and size no longer cause problems. Very large photos no longer make the upload fail. - Error messages now show in your language and tell you what to do, instead of technical French text or a "JSON error". Reminder: you need a real screenshot of the dyno screen with the orange cursor visible, never a photo of your screen. On mobile, crop it to keep only the chart. The new suspension, alignment and differential values come from player tests. If your car behaves differently, let us know, and adjust them to your driving. Your existing builds already show the new values, nothing to redo.

New: the Premium plan An optional paid subscription for players who want more than the free plan. The free plan keeps the full setup calculation (gearbox, differential, suspension, alignment, brakes), with 10 builds at most and 6 dyno analyses per build per month. Premium adds: unlimited builds, full version history with comparison between any versions, folders to organise your builds, a side-by-side comparison of two builds, private or expiring share links with view and clone stats, PDF export of the setup sheet, an email when someone clones one of your builds, a badge shown in the gallery, priority handling of your feedback, and no ads. Payment goes through Stripe. You can cancel in one click, and you have 14 days to withdraw after subscribing. New: the Premium+ plan On top of Premium, two more features. The first: an AI assistant on every build page. It reads your results and your questions, proposes settings recalculated by the tool, and you decide whether to apply them. It does not replace the calculation, it works from it. The second: editing any result value directly on the build page. Click a value, change it, it is saved. The value calculated by the tool stays shown next to it, and values that depend on it (speed per gear, suspension frequencies, anti-roll bars) recalculate automatically. New: comparison, history and folders A button to compare two builds from your garage, showing only the fields that differ. Version history already let you compare two versions of the same build, it is now unlimited on Premium. Folders let you sort your builds by discipline, car or event. New: paste a dyno screenshot from your clipboard On PC, Ctrl+V anywhere on the dyno step of the form pastes your capture directly, no file browser needed. On mobile, a "Paste" button does the same. Drag and drop also works. New: search, filters and sorting on your builds The builds page now has a search bar, a filter by discipline, and sorting by date, name, power or weight. Changed: the site moved to carx-bo.com New domain, same tool, same account. Update your bookmarks. Fixed: the Stock and Sport fuel labels on step 1 of the form, which showed raw text instead of an explanation.

Changed: the differential no longer depends on your gearbox The coast lock, the preload and the front axle lock were computed from torque in 2nd gear. Changing gearbox therefore changed your differential. That is over: it no longer depends on your gearbox, your final drive or your number of gears. What is computed, and what is a choice: - Rear acceleration lock: computed from your chassis and tyres (previous version). - Rear coast lock: 0.3. It is a "1.5-way" tuning choice, for stability on turn-in. It is not a calculation. - Preload: 0.4 times the engine's peak torque, per axle. It is a choice, close to what the tool suggested on average. No measurement determines it. - Front of front-wheel and all-wheel drive cars: little acceleration lock (0.4 front-wheel drive, 0.3 all-wheel drive), no coast lock, preload half the rear's. This is the usual setting for a steered axle. - Drift: locks at 1.0 as before, preload independent of the gearbox. - Drag: acceleration lock at the maximum on every driven axle, rear coast lock at 0.3, reference preload. What it changes for you: - The rear coast lock becomes 0.3 everywhere (it was half the acceleration lock, so between 0.2 and 0.35). - On front-wheel drive and the front of all-wheel drive, the acceleration lock drops noticeably (a Golf in our database goes from 0.68 to 0.4). Preloads change depending on the car, slightly downward on average. - These values are choices, not calculations. Adjust them to your driving. None of this is validated in game.

Updated the way gearboxes are handled in the build form, now you just need to select your gearbox, your gearbox parts and that's it ! Now gearbox ratios stay at default values, the only thing that changes is the final drive, typically the most important value to tweak. Calculations were tested with every race paths existing in game, and i finally found that the default gearbox values are the best values you can get. For the differential, it changed its values based on the 2nd gearbox ratio. Happy tuning !

New: fuel choice (Stock / Sport) The in-game garage ignores sport fuel: the values you read there (rev limiter, torque, dyno curve) are stock-fuel values. Keep entering them as they are, the tool now applies the fuel for you: - Sport: rev limiter +5% (e.g. 7999 → about 8400 rpm), torque and power +10%. - Pick it with radio buttons in step 1 of the build (create and edit), and switch it in one click from an existing build's page. All results are recalculated and the change shows in the version history. - Your existing builds stay on Stock fuel; nothing changes until you switch. New: older builds upgraded On the page of a build created before some features existed, a "Fetch game data" button fills in the missing info about your car (aerodynamics, stock dampers…). Only empty fields are filled: your values are never overwritten. Recommendations (tires, theoretical top speed) also work on older builds. Improved: gearbox - The top gear is better placed when your top speed is drag-limited: it reaches its top speed at the top of the powerband instead of leaving unused revs. A target top speed within 1.5% of the theoretical limit is now treated as that limit. - The top speed calculation accounts for transmission loss (20% in game). - Tested in game on a Supra A90: 304 km/h predicted, 303 measured. Improved: tires, anti-roll bars and mobile - Fixed saturated anti-roll bars on grip and track setups. - Mobile app (PWA): bottom navigation, the page finally ends where it should on phones, and the site can be installed. - Build wizard: when a field is invalid, a summary tells you which one and takes you there, instead of silently sending you back a step. - Class calculation rounds down to the lower class until the +0.8 threshold is exceeded.

NEW FEATURES ------------ Build history & versioning Every time you edit a build, a snapshot of its previous state is saved automatically. New pages let you browse the full history of a build and compare any two versions side by side, field by field. The Garage - ranks & badges A new profile page tracks your progress as a tuner. Earn XP from real activity (builds created, versions iterated, dyno analyses run, builds shared, feedback sent) and climb through six ranks, from Garage Rookie to Circuit Legend. Unlock 9 badges along the way (first build, 5+ iterations on one build, pinpoint-accurate Vmax, 10 dyno analyses, a build cloned by another player, 100+ views on a public build, a feedback that got a reply, builds across 4+ disciplines, 30+ days as a member) - a popup lets you know the moment you unlock one. Interactive feedback Feedback you send is no longer a one-way message. The team can now reply directly from the admin panel, and you'll get notified both by email and with an in-app popup the next time you visit. Builds list improvements Search your builds by name or car, filter by driving discipline, and sort by date, name, power or weight - all live, no page reload. Community gallery: filter by class The public gallery can now be filtered by power class (C1 through CS+), on top of the existing discipline, car and sort filters. Build sharing: any engine or gearbox is now swappable The "installed parts" sheet used to only offer the handful of swaps the game natively lists for your specific car. It now offers every engine and every gearbox in the game, matching what's actually possible in-game. When two cars share the exact same real-world engine (several BMWs run the S58, for example), the list now tells them apart by naming the source car instead of showing the same label twice. IMPROVEMENTS ------------ - Sidebar navigation redesigned: icon chips, gradient highlight matching the app's identity, and a subtle decorative glow - plus a live preview of your current Garage rank right in the sidebar. - Wiki updated to document features that existed but were never explained: the Garage, the class optimizer, and the community gallery. - App renamed to "CarX Street Build Optimizer" across the site for better discoverability. - Admin: users list now sorts online/recently active players first, and feedback needing a reply surfaces at the top with a clear badge. - Admin stats: the "by player" table is now paginated instead of loading every account at once. BUG FIXES --------- - Fixed a bug where editing a build could show stock/default values instead of your saved data, if a leftover autosave draft silently reselected the car and triggered a full form reset. - Fixed charts (admin stats, build dyno curves, engine simulator) not loading on first navigation to a page - a race condition between Chart.js loading and the page's own script under Turbo navigation. - Fixed a crash on the profile page ("Array to string conversion") and restored the Profile/Password section headers, which had been invisible due to a leftover animation class from an unrelated wizard component. - Fixed stale engines/gearboxes/parts lingering forever after a game update changed or removed them - the game data importer now cleans up anything no longer present in the latest bundle. - Removed the "Cooling" engine slot and capped Body Strengthening at ST4 in the parts sheet - both existed in the raw game data but aren't actually usable in the real tuning menu. - Fixed car real names still showing in French in a few places.

New: Public build sharing Every build now features a "Share" button (on its details page, next to "Edit"). This opens a two-part form: 1. Visibility: a "Make this build public" checkbox. Once checked and saved, a unique link is generated (/b/xxxxxxxxxxxx)—this is not the build ID itself, ensuring that private builds cannot be discovered simply by guessing a number. You can switch back to private at any time; the link remains the same if it has already been shared, but it simply becomes inaccessible. 2. In-game installed parts: the form lists—specifically for your car—everything that can actually be selected in the garage: - Engine: stock or swap, with fields that update automatically based on the chosen engine (block, camshaft, turbo, ECU, etc.) - Swapped transmission + related parts (gearbox, clutch, differential, AWD/FWD/RWD drivetrain) - Body kit + body parts (weight reduction, chassis reinforcement, front/rear aero, fuel tank) - Suspension (springs, dampers, anti-roll bars, arms, brakes) - Rims, tires, and front/rear spacers Anything not specified remains "stock": you only declare what you have actually changed. The lists show only parts compatible with your car (compatibility rules are re-verified server-side upon saving). The public page (/b/xxxxxxxxxxxx) is viewable without an account, indexable by search engines, and displays the exact same result tables as your private profile (transmission, differential, suspension, alignment)—with no personal details exposed other than your username as the author. A visitor can: - Copy the link to share it (e.g., YouTube comments). - "Use as a base": if they have an account, this copies the build into their own garage so they can adapt it to their car (or create a free account). - View "Also discover" builds (prioritizing the same car, otherwise the same discipline). New: community gallery (/community, also accessible without an account): all public builds in one place, organized by car and sortable by date or popularity (view count). A preview of the latest shared builds also appears on the homepage. Technical note for your eyes only: public view counts automatically exclude your own visits (detected via your session), and no cookies or IP addresses are stored for this—this is a best-effort implementation.

The Drag discipline is now available. The build form includes a dropdown listing every Drag race in the game, grouped by district: picking a race automatically sets the target distance used to optimize your gearbox, no more manual input needed. The form has been reorganized for readability: technical fields you never need to touch yourself (wheelbase, front/rear track width, tire grip) are now hidden and computed automatically, instead of sitting next to the fields you actually need to fill in. First version of a tire recommendation (width, rim, spacer) tailored to your chosen discipline, with a button to apply it directly to the build. This feature is still in early testing and its rules will likely keep evolving.