The RM GT4+ program brings the front splitter, canards and rear wing together around the BMW G87 M2. Understanding that package means looking beyond individual parts: the bumper, wheels, underbody, roof and rear glass all influence the airflow reaching each aerodynamic surface.
This article explains the published G87 CFD results, the role of each component and what those findings mean for a track-focused setup.
QUICK ANSWER
The analyzed configuration produces 489.2 lbf of net downforce and 369.2 lbf of drag at 120 mph when scaled from the report’s native test speed. The reported aerodynamic load distribution is 48.5% front / 51.5% rear.
The underlying full-vehicle simulation was conducted at 100 km/h (62.14 mph), with the rear wing in position 2. The 120 mph figures use velocity-squared scaling; they are not a separate simulation at that speed. Read the G87 GT4+ CFD report →
WHAT MAKES UP THE G87 GT4+ SYSTEM?
- Front splitter: a carbon lip and air dam, tunneled lower splitter and chassis support.
- Canards: vehicle-specific dive planes shaped around the G87’s front bumper.
- Rear wing: a 1600 mm carbon mainplane, endplates and swan-neck supports with G87-specific mounting bases.
Each component has a different role. The useful question is how they work within the airflow of the installed vehicle.
FRONT SPLITTER: PRESSURE CONTROL WITH STRUCTURAL SUPPORT
The splitter combines an upper lip and air dam with a tunneled lower surface. Its brackets transfer aerodynamic load to the front structure, giving the surface the support it needs at speed.
The report’s splitter surface forces scale to 152.9 lbf of downforce and 26.3 lbf of drag at 120 mph, with a reported downforce-to-drag ratio of 5.81. The pressure and underside-flow visualizations help explain where that load develops.
These figures describe the selected splitter surfaces. They are not the front axle load, and they do not establish the gain over a stock splitter by themselves.
EXPLORE THE G87 GT4+ FRONT SPLITTER →
REAR WING: EVALUATED IN THE G87’S AIRFLOW
Air reaching the rear wing has already traveled over the hood, roof and rear glass. Acceleration and separation across those surfaces change the wing’s incoming flow, which makes the installed vehicle an important part of the analysis.
With the wing in position 2, its reported surface forces scale to 245.0 lbf of downforce and 12.3 lbf of global-X drag at 120 mph. The corresponding ratio of 19.87 belongs to this installed configuration and force convention; it should not be treated as a universal isolated-wing efficiency rating. The report does not define position 2 as a geometric angle.
The swan-neck supports attach above the mainplane, keeping the lower wing surface clear of conventional underside mounting brackets.
EXPLORE THE G87 GT4+ REAR WING →
CANARDS: PART OF THE FRONT AERO CONFIGURATION
The canards follow the G87 bumper’s shape and complement the splitter. The published imagery shows the flow around the bumper and front wheel, providing useful context for the front aero configuration.
The report does not publish an isolated canard-force result, so this article does not assign the canards a standalone downforce gain.
EXPLORE THE G87 GT4+ CANARDS →
HOW TO READ THE RESULTS
The figures below are scaled to 120 mph from the same 100 km/h analysis. Downforce is shown as a positive magnitude.
| Analyzed surfaces | Downforce (lbf) | Drag (lbf) |
|---|---|---|
| Whole vehicle | 489.2 | 369.2 |
| Front splitter | 152.9 | 26.3 |
| Rear wing | 245.0 | 12.3 |
Rear-wing drag uses the report’s global-X force convention. Component surface forces and axle loads are different quantities.
The body also contributes forces, and each force’s position creates a pitching moment. Adding component downforce figures does not directly reproduce the front/rear axle distribution.
Velocity-squared scaling assumes the aerodynamic coefficients, air density and vehicle attitude remain unchanged. The published report does not document mesh resolution, turbulence model or y+ values, so those details are not borrowed from the separate Supra development program.
VIEW THE ORIGINAL G87 CFD REPORT →
FROM ANALYSIS TO TRACK USE
THE HARDWARE: the G87 GT4+ front aero installed on the track car.
Built within one month, John Cruz’s G87 recorded 1:34.46 at Laguna Seca on 275-width, 200TW Yokohama A052 tires. The setup retained the stock brakes, turbos and transmission, with no weight reduction, a downpipe, REMARK exhaust and an off-the-shelf MHD Stage 2 OTS tune on 91-octane pump gas, without flex fuel. S3 suspension with an MSRP of $1,699 and the full SPL parts catalog provide chassis adjustment, while RECARO RMS seats and a JQ WERKS Madtrace Gen 2 Podium Line system complete the cockpit. The lap was achieved under Street Mod’s 275-width / 200TW tire limit.
That lap is a result of the complete car, its tires, setup and driver. It does not isolate the lap-time contribution of aero. It does show the context for the GT4+ program: functional aerodynamic hardware integrated into a coherent, accessible track build.