When it comes to performance tuning, the difference between looking fast and being fast is science. At ASM Tuning, weโve built our reputation not just on bold design and premium carbon fibre construction โ but on measurable aerodynamic performance.
This blog marks the official release of the CFD validation results for our dry carbon spoiler for the BMW G87 M2. The data speaks for itself: more grip, more stability, and zero guesswork.
Welcome to the next chapter in engineered aero.
Why CFD Testing Matters in the Tuning World
CFD (Computational Fluid Dynamics) is an advanced simulation method that uses mathematical modelling to replicate how air flows around a surface. Itโs the same aerodynamic testing tool used in Formula 1, aviation, and high-end OEM development programs.
By applying CFD to our components, we can:
- Quantify aerodynamic pressure distribution
- Visualize turbulence, separation, and wake behaviour
- Measure forces like lift (downforce) and drag
- Balance performance gains with real-world driveability
Most importantly, CFD separates real aero performance from parts that are purely cosmetic.
The Platform: 2023+ BMW G87 M2
The G87 M2 is a beast straight from the factory: short wheelbase, wide fenders, and a twin-turbocharged inline-six. While its aggressive stance and powertrain set it apart, the OEM spoiler provides minimal aerodynamic benefit โ offering style without real downforce.
ASMโs objective was simple:
โDesign a spoiler that looks OEM+, but delivers track-proven aerodynamic performance.โ
Our CFD Test Setup
To validate our spoilerโs performance, we used SimScale, a cloud-based engineering-grade CFD tool trusted by professionals in motorsport and industry.
Simulation Details:
- Simulation type: Steady-state external aerodynamics
- Velocity inlet: 140 km/h (38.89 m/s)
- Turbulence model: Realizable k-ฮต
- Tested geometry: Rear trunk volume (spoiler zone only)
- Boundary conditions: Symmetrical half-model, flat ground plane
- Data collected: Pressure fields, velocity fields, force coefficients (Cl, Cd, Cm)
Two test cases were run:
- Without the spoiler (baseline)
- With the ASM G87 M2 dry carbon spoiler installed
Results Summary
Net Downforce:
356.6 N, or 36.3 kg of aerodynamic load applied to the rear axle at 140 km/h.
This provides significantly improved high-speed rear grip and stability โ ideal for track days, fast road driving, and spirited highway runs.
Drag Force Added:
Only 17.6 N, or 1.8 kg of aerodynamic drag.
This small increase reflects the spoilerโs clean airflow integration and optimized profile โ maintaining performance without hurting top-end speed or efficiency.
Lift-to-Drag Ratio (L/D):
20.2 : 1
That means for every 1 kg of drag added, youโre gaining over 20 kg of usable downforce โ a sign of outstanding aerodynamic efficiency.
Visualizing the Airflow: CFD Flow Results
Without Spoiler:
- The airflow detaches early from the rear edge of the trunk.
- Large turbulent wake behind the car reduces pressure stability.
- Rear lift remains high, with minimal downforce generated.
With ASM G87 M2 Carbon Spoiler:
- Airflow is redirected downward over the spoilerโs surface.
- Streamlines remain attached longer, creating a strong low-pressure zone behind the car.
- Wake narrows and stabilizes, improving aerodynamic consistency.
- Downforce is generated without disrupting vehicle balance.
Balanced Aerodynamics for Real Driving
Aero performance isnโt just about downforce โ itโs about balance.
Too much rear grip without front aero can create understeer. Too little downforce can result in instability. Thatโs why we also analysed the moment coefficient (Cm) to ensure our spoiler keeps the car neutral and confidence-inspiring at speed.
With the ASM G87 M2 Carbon spoiler:
- Rear axle sees improved load distribution
- Braking remains stable at high speeds
- Cornering grip increases without rear-end instability
How CFD Works โ In Simple Terms
Curious how this all works behind the scenes?
CFD uses Navier-Stokes equations โ the mathematical laws that govern fluid flow โ to simulate how air behaves when passing over a car. These simulations show how the shape of the spoiler:
- Changes the velocity of airflow (Bernoulliโs principle)
- Creates a pressure difference between the top and underside
- Generates a net vertical force (downforce)
Even subtle changes in angle, profile, or curvature can shift the results dramatically.
Thatโs why our spoiler wasnโt just designed โ it was engineered, simulated, and refined.
Real-World Driving Impact
So what does 36.3 kg of downforce actually feel like?
At 140 km/h, itโs the equivalent of adding a heavy passenger directly over your rear axle, except this โpassengerโ is aerodynamic โ it doesnโt affect your ride height, suspension, or unsprung weight.
Youโll notice:
- ย Tighter rear-end grip on long sweepers
- More confidence when braking from high speed
- ย Less lift when cresting hills or high-speed curves
- ย Improved throttle stability mid-corner
This is usable, measurable performance that translates into a more planted, responsive, and enjoyable driving experience.
A Word from Our Engineering Team
โToo many aero parts are built for show, not function. At ASM, we believe in data-backed design. CFD allows us to validate what the driver will actually feel behind the wheel โ and this spoiler delivered. Itโs OEM+ in look, but beyond-OEM in performance.โ
โ ASM Engineering Division
Why OEM+ Fitment Matters
Even the best aero is useless if it doesnโt fit.
Thatโs why we engineered this spoiler to:
- Match OEM trunk curve and contour
- Use the correct mounting tolerances
- Be lightweight but rigid (dry carbon pre-preg construction)
With OEM+ fitment and real aerodynamic function, the spoiler enhances your M2โs lines while boosting its capabilities.
Download the Full CFD Report
Want to dive deeper into the data?
Our technical report includes:
- CFD simulation setup
- Pressure and velocity overlays
- Force coefficient convergence plots
- L/D ratio breakdown
- Final summary and validation
Download ASM G87 M2 Spoiler โ Aerodynamic Performance Report (PDF)
Frequently Asked Questions (FAQ)
Q: Is this spoiler just for the track?
A: No โ itโs designed for high-speed street use and occasional track driving. It improves confidence in real-world conditions without being overly aggressive.
Q: Will it affect fuel efficiency?
A: Negligibly. The added drag is just 1.8 kg at 140 km/h โ the impact is minimal for daily use.
Q: Do I need to upgrade the front aero too?
A: Itโs not required, but for a fully balanced aero package, a front splitter or canards will further stabilize front-end lift.
Q: Whatโs the difference between this and the OEM M2 spoiler?
A: The OEM unit is mainly for appearance. The ASM spoiler adds ~36.3 kg of rear downforce, improving real performance with minimal drag.
Whatโs Next: CFD for the Full ASM Components Collection
This spoiler is just the beginning. Weโre now CFD-testing the full ASM Design Collection to ensure every part delivers verified aerodynamic benefit.
Coming soon:
- Front Splitters
- Rear Diffusers
- Side Skirts
- Intake Ducts and Grilles
- ASM Forged Wheels & more
Each part will be tested, refined, and backed by published aerodynamic data.
If it wears the ASM logo, youโll know itโs not just built to fit โ itโs built to perform.
Ready to Upgrade?
Youโve seen the numbers. Youโve read the data. Now feel the difference.
Dry carbon construction
OEM+ fitment
356.6 N of real downforce
CFD-validated
Worldwide shipping
[Explore the ASM G87 M2 Spoiler]
[View the Full ASM Aero Collection]
Final Words
In a crowded aftermarket world full of untested claims and โaero-lookโ accessories, ASM Tuning is committed to proving performance through engineering.
The G87 M2 deserves more than a cosmetic add-on โ it deserves an aerodynamic upgrade that transforms stability, grip, and confidence.
With CFD-proven aero, weโre not guessing.
Weโre engineering real performance.
