If you want to make the case that the last thing a BMW M4 Competition needs is more performance, you won’t struggle to find others who agree. The latest G82 generation model and its G80 M3 sibling push the concept of a car punching above its weight class to extremes.
A 503-horsepower straight six makes world-beating acceleration the norm, while an optional all-wheel drive system all but assures backroad dominance. For those who want more, BMW answered the question before you asked it, first with the stripped-out M4 CSL and then with the spiced-up M4 and M3 CS. What, then, is there left to improve?
CarBahn, the latest venture by legendary tuner, racer, and engine builder Steve Dinan, believes it found a compelling counterargument in the form of its $20,599 CB3 Signature Package.
Before the first miles come, there’s good reason to expect greatness from this car. While CarBahn isn’t yet a household name, Dinan certainly is, with his strong reputation for reputation for modifying and racing cars stretching back to the early 80s. Although he’s no longer part of the company that bears his name, Dinan’s philosophy of upgrading cars to OEM or better standards while matching the factory warranty endures.
Understanding that mindset is crucial to grasp what this car is ultimately going for. At first, when you read that this BMW M4 Competition no longer produces the stock 503-hp figure but instead a McLaren 720S-beating 735 hp, it would be easy to assume that CarBahn dials up power beyond factory limits and calls it a day.
The opposite is true. The surge in performance begins with custom engine software, also boosting its torque output to 668 pound-feet, an upgraded heat exchanger, and a new cold air intake to ensure this two-door remains as reliable as possible. The final piece to CarBahn’s Stage 2 Power Package is a new stainless steel exhaust. However, this tester swaps it out in favor of lighter pipes made of titanium for $3,500.
While an extra 232 hp and 189 lb-ft represent a leap forward performance-wise, these aren’t the most impactful upgrades bolted to this all-wheel-drive-equipped M4.
For that, you’ll have to turn to its reworked suspension. The first item on the list is what the tuner calls a “coilover kit,” but it isn’t so in the traditional sense that it replaces both the spring and damper. Instead, it adds height-adjustable springs while retaining the stock damper, ensuring that the versatility of the factory suspension modes remains. However, CarBahn crafted adjustable bump stops to support it, which might initially seem relatively minor but significantly impacts ride quality.
As the spring compresses, these bump stops can absorb excess energy produced by road imperfections, limiting the roughness felt in the cabin. This makes this BMW M4 Competition firmer while improving its ability to remain perfectly settled on a bumpy road. It decision also results in a more compliant ride for daily use.
Alongside the coilover kit, CarBahn’s CB3 Signature Package includes adjustable anti-roll bars, Monorail bushings up front, and upgraded toe links in the rear. A five-point carbon strut brace improves chassis rigidity, while stainless steel brake lines support consistent performance while slightly firming up the pedal. It’s worth noting, however, that the tuner optioned this particular M4 from new with a set of $8,150 carbon ceramic brakes.
The most expensive CarBahn option fitted to this car is one you shouldn’t skip. For $4,000, it gains a widened set of 20-inch forged wheels, seen here in a dark bronze finish, and Michelin Pilot Sport Cup 2 R rubber. This car’s track broadens thanks to tires that measure 295/30 up front and 305/30 in the rear.
Cosmetically, the Signature Package loads this car’s exterior with carbon fiber goodies. It starts beneath the hood with an engine cover, works its way out to a motorsport-inspired grille, and finishes off with a complete body kit made of the lightweight material. The result is a two-door with an aesthetic and a stance far more aggressive than anything BMW would ever mass-produce.
Now that you know all the details, how effective are they?
The answer is that they’re nothing short of transformative. On a winding back road, you’ll feel the effects long before you pick up the pace. While a stock BMW M4 Competition incorporates an ultra-quick steering rack in hopes of making you think that this nearly 4,000-pound two-door is lighter and more agile than it is, there’s still a split-second delay as its heft catches up.
This isn’t the case in the M4 by CarBahn. Thanks to its upgraded suspension and wider tires, this two door changes direction without hesitation. With a sharpened response from the front end, tackling a winding road now feels like a much more cohesive and seamless experience. You get exactly what you ask of it the moment you turn the wheel.
While these updates don’t unmute BMW’s utterly dead electric power steering system, you get slightly more weight as you load up in the bends, while feedback from the chassis is improved. Braking performance is fantastic, but then what would you expect from a car wearing a nearly five-figure set of carbon ceramics?
It helps that you’re lugging around less weight, too, with CarBahn’s forged wheels and titanium exhaust shaving a few pounds. According to CarBahn, with those options fitted alongside BMW’s carbon ceramics and carbon seats, this car weighs 200 fewer pounds than a base xDrive-equipped M4 Competition.
Even as you pick up your pace, this BMW M4 Competition remains effortlessly composed in both open and tight bends. Even large bumps struggle to unsettle it as it feels significantly more hunkered down than a factory car would. Yet, despite feeling more planted, it never translates road harshness to its occupants, thanks partly to its new bump stops.
The result is a car that moves perfectly instep with its driver while delivering a driving experience more focused on providing fun than outright performance.
That said, its extra 232 horses are certainly all accounted for. Yet despite it accelerating more ferociously than a stock car, it’s never overwhelming. Thanks to its xDrive system, it doesn’t struggle for traction. It remains perfectly composed even as you route the power exclusively to its rear wheels.
Its titanium exhaust allows its 3.0-liter inline-six to be far more vocal but never excessively on the highway or during everyday commuting. Still, it’s limited by the fact that BMW’s raspy S58 engine is far from its best sounding.
More magic can be found as you turn off the twisty road and assign this BMW M4 Competition daily driving duties. Despite its massive 295-width front tires, it doesn’t tram line, nor is the in-cabin noise excessive. However, the plushness felt on a bumpy road remains, significantly increasing this car’s comfort and versatility. While you’ll get a slight hint of fender and tire contact while maneuvering at full lock, it quiets down the second you turn the wheel back.
While the CB3 Signature Package costs $20,599, this tester sports the aforementioned $3,500 titanium exhaust system, a $4,000 wheel and tire package, and a $1,500 factory-matching four-year/50,000-mile warranty.
The M4 Competition xDrive used for this build costs $98,145 thanks to extras such as its $8,150 carbon ceramics and $3,800 m carbon bucket seats. This brings the total cost up to $127,744. that’sThat’s comparable to the M4 CS’ $124,675 base price for context.
To answer the original question, this BMW M4 Competition by CarBahn isn’t designed to find fault and improve an otherwise fantastic sports car. That’s the route chosen by the CS and CSL models, effectively amplifying the stock experience with a more hardcore approach.
Instead, Steve Dinan employs masterful tuning work to offer us something different. This M4 doesn’t fall anywhere within the CS to CSL binary. It modifies enough to stand on its own. It doesn’t make the case that this car needs any additional performance; it instead asks: “What if we not only give you more, but we make it more approachable, enjoyable, and daily usable?” as it shows, this is the question truly worth asking.