What GT3 and GT4 actually are
GT3 and GT4 are both real, FIA-recognized homologation classes created by SRO Motorsports Group to organize grand tourer racing into two clearly separated tiers rather than one open free-for-all. GT3 sits at the top: purpose-built race cars that share only a body silhouette and badge with the road car they're named after, built by manufacturers specifically to compete. GT4 sits directly below it as SRO's deliberately lower-cost, more production-based entry tier, built to stay meaningfully closer to the actual road car underneath.
Both classes exist across dozens of national and international championships worldwide, and both use the same underlying fairness mechanism — Balance of Performance — but the cars, budgets and grids they produce are genuinely different animals.
Both grids are built entirely from real manufacturer entries competing head-to-head under the same class rules. Current GT3 grids include the Ferrari 296 GT3, Porsche 911 GT3 R (992), Mercedes-AMG GT3, Lamborghini Huracán GT3 EVO2, BMW M4 GT3, Ford Mustang GT3 and Aston Martin Vantage GT3. Current GT4 grids include the Porsche Cayman GT4 RS Clubsport, BMW M4 GT4, Aston Martin Vantage GT4, McLaren Artura GT4 and Toyota GR Supra GT4 — recognizably the same manufacturers, one tier down.
Spec-by-spec comparison
The real, sourced numbers make the gap concrete rather than abstract:
| Spec | GT3 | GT4 |
|---|---|---|
| Horsepower | ~500-600+hp | ~400-450hp |
| New car cost | $400,000-$600,000+ | $150,000-$250,000 |
| Base vehicle | Purpose-built race car sharing only a silhouette with its road car | Must stay much closer to its production road-car origins |
| Aerodynamics | Extreme: large adjustable wings, front splitters, underbody diffusers | Limited, closer to what a road car could plausibly run |
| Homologating body | FIA Group GT3 | FIA Group GT4 (certified via Belgium's RACB) |
| Balance of Performance | SRO-administered, adjusting power/weight/aero for parity | SRO-administered, same underlying mechanism |
| Typical grids | IMSA GTD/GTD Pro, GT World Challenge, WEC LMGT3, Nürburgring 24h SP-X | GT4 European Series, GT America, ADAC GT4 Germany, club and Am-friendly grids |
Cost is the real dividing line
A new, factory-built GT3 car costs somewhere between $400,000 and $600,000 depending on manufacturer — Porsche and Ferrari sit toward the top of that range — before a season's running costs, tires and crew are even added. A GT4 car costs roughly a third to a half of that, generally $150,000-$250,000 new, with correspondingly lower running costs for parts, tires and maintenance across a season. That gap is entirely deliberate: GT4 was created specifically to give teams and gentleman drivers a genuine GT racing experience without GT3's escalating factory-level budget.
Balance of Performance: how both stay fair
Both classes rely on Balance of Performance (BoP), a regulatory mechanism SRO administers to keep wildly different manufacturer platforms competitive against each other by adjusting power output, minimum weight, fuel-tank size and aerodynamic parameters race by race. Without BoP, a class built around a dozen different manufacturers' cars — Porsche, Ferrari, Mercedes-AMG, Lamborghini, BMW, Aston Martin and others, across both GT3 and GT4 — would simply be won by whichever platform happened to have the biggest inherent performance advantage, rather than by driver and team execution.
Where each class actually races
GT3 machinery is the backbone of professional sportscar racing worldwide: IMSA's GTD and GTD Pro classes, SRO's GT World Challenge America, Europe and Asia, the Asian Le Mans Series, and — since 2024 — the WEC's own LMGT3 class, which replaced the previous GTE category as the World Endurance Championship's production-based GT tier. See our explainer on WEC's Hypercar and LMGT3 multi-class racing for how that class fits into endurance racing's wider structure.
GT4 racing lives one level down, aimed more deliberately at Am and Pro-Am teams: the GT4 European Series, GT America, ADAC GT4 Germany, and as a common support or entry class at events like the Nürburgring 24 Hours, where it often runs as one of several classes on the same grid rather than as its own standalone championship.
Pro-Am driver ratings: a system unique to GT racing
Both GT3 and GT4 racing rely on a driver-rating system almost no other motorsport discipline uses this formally: drivers are classified Platinum, Gold, Silver or Bronze based on their professional racing history and results, and many championship classes then require a specific mix within each car's driver lineup. IMSA's GTD class, for example, requires at least one Silver- or Bronze-rated driver per car and limits each entry to a single Platinum-rated driver, specifically to keep the class genuinely open to talented amateurs racing alongside professionals rather than becoming an all-professional field by default.
Which class should a new fan actually follow?
GT3 offers the faster cars, the bigger manufacturer names and the higher-profile grids — IMSA GTD Pro and WEC's LMGT3 class are where GT racing's most visible professional competition happens. GT4 offers a genuinely more accessible, budget-conscious version of the same sport, with grids built deliberately around gentleman drivers and smaller teams rather than factory-level budgets, and it's often the class where the next generation of GT3 drivers first cut their teeth.
See our complete guide to endurance racing for how both GT classes fit into the wider world of multi-class sportscar competition.
Frequently asked questions
What is the main difference between GT3 and GT4 cars?
GT3 cars are purpose-built race cars producing 500-600+hp that share only a body silhouette with their road car namesake, while GT4 cars stay much closer to their actual production road car and produce roughly 400-450hp.
How much does a GT3 car cost compared to a GT4 car?
A new GT3 car costs roughly $400,000-$600,000+ depending on manufacturer, while a new GT4 car costs roughly $150,000-$250,000 — about a third to a half of GT3's price.
What is Balance of Performance in GT racing?
A regulatory mechanism administered by SRO Motorsports Group that adjusts each car's power, weight, fuel capacity and aero parameters to keep different manufacturer platforms competitive against each other, used in both GT3 and GT4.
Which racing series use GT3 cars?
IMSA's GTD and GTD Pro classes, SRO's GT World Challenge America, Europe and Asia, the Asian Le Mans Series, and the WEC's LMGT3 class, which replaced the GTE category starting in 2024.
Which racing series use GT4 cars?
The GT4 European Series, GT America, ADAC GT4 Germany, and as a common entry or support class at events including the Nürburgring 24 Hours.
What are Platinum, Gold, Silver and Bronze drivers in GT racing?
A driver-rating system classifying competitors by professional experience and results. Many GT3 and GT4 championship classes require a specific mix — IMSA's GTD class, for instance, requires at least one Silver- or Bronze-rated driver per car and allows only one Platinum-rated driver.
Is GT4 a feeder class for GT3?
Informally, yes — GT4's lower cost and more production-based cars make it a common step for drivers and teams before moving up to GT3's faster, more expensive machinery, though it's also a genuine standalone racing category in its own right.
Who homologates GT3 and GT4 cars?
GT3 cars are homologated under the FIA's Group GT3 regulations. GT4 cars are certified through Belgium's RACB, with both classes' Balance of Performance administered by SRO.
Are GT3 and GT4 cars based on real road cars?
Both are, but to very different degrees. GT4 cars must stay meaningfully close to their production road car. GT3 cars share only a body silhouette and manufacturer badge — the underlying chassis, aero and powertrain are purpose-built for racing.
What cars currently race in GT3 and GT4?
Current GT3 grids include the Ferrari 296 GT3, Porsche 911 GT3 R, Mercedes-AMG GT3, Lamborghini Huracán GT3 EVO2, BMW M4 GT3 and Ford Mustang GT3. Current GT4 grids include the Porsche Cayman GT4 RS Clubsport, BMW M4 GT4, Aston Martin Vantage GT4, McLaren Artura GT4 and Toyota GR Supra GT4.
What replaced GTE cars in the World Endurance Championship?
LMGT3, introduced in 2024, replaced the previous GTE category as the WEC's production-based GT class, running alongside the top-tier Hypercar class.
Sources
Priya covers endurance racing, NASCAR and drifting for CNMOTOS, drawn to disciplines that reward either sustained consistency over 24 hours or outright commitment in a single tandem battle.
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