Royal Guard – 2021+ BMW G8X M3/M4 Skid Plate R&D, PART 1 – Design Plans and Prototyping

The BMW M3 and M4 are automotive royalty. They’re the lords of the compact executive sports car segment, and BMW intends to keep it that way. Last year we saw the coronation of the latest prince of posh speed, the G8X, and this generation is the most power-hungry yet. These dignitaries are hell-bent on dominating not only their class but every inch of asphalt as we know it. The trouble is, the road is a feral and unpredictable creature, prone to lashing out at vehicles. The G8X may be a valiant crusader, but it still has vulnerabilities, specifically at its underbelly.

When designing the M3, BMW aimed for a perfect balance of performance, comfort, and attainability. Essentially, some of the G8X’s components required a design that simplified manufacturing in masse without increasing production costs even further. One of those components is the front skid plate, resulting in a protective barrier made of flexible plastic that’s assigned to safeguard the oil cooler.

For those unaware or who need a refresher, BMW mounts the oil cooler perpendicular to the rest of the cooling stack and utilizes the M3’s aerodynamics to direct air through the cooler’s fins and regulate oil temperatures. Specifically, on the G8X platform, the factory skid plate features a short lip that creates a low-pressure zone to further direct air through the cooler.

Click here for a closer look at the G8X platform’s oil cooler

On paper, this concept is ideal for engineers conscious about packaging while promoting efficient cooling for their sporty sedan, but it’s a double-edged sword. This design leaves the oil cooler in a low and precarious position, prime for punctures or worse. While the rest of the M3’s undercarriage is plated in metal, this critical component is shielded in plastic and not entirely up to the task of guard duty, especially when these low-slung Bimmers get even lower.

In the automotive world, you’re only as strong as your weakest link, so we’re already hard at work beefing up the security on the underside of the G8X. To start, our engineer, Dave, gets his plan into place, starting with scanning the OEM undertray with our Faro Design ScanArm to create a virtual workspace that helps streamline our R&D process.

With the OEM tray copied, it was time to start thinking about material choices. Since this is destined for the lord of the sport compact, we need to focus on the ideal balance between performance and protection. Basically, it needs to shrug off road debris without tipping the scales, all with the added goal of staying affordable. With that in mind, Dave opted for a complete aluminum construction that checks all three marks.

Since one of our primary goals is to have this plate fit like BMW installed it, the overall shape of our skid plate doesn’t deviate much from the stock component. Besides the material update, our most notable update is the extra layer of defense we incorporated around the oil cooler. This added aluminum grate is specifically designed to ward off rogue road debris while promoting airflow through the oil cooler’s core. We also carried over the front air dam to retain the same low-pressure zone to promote aerodynamics further. Finally, to top things off and keep this plate secured to the bottom of the M3, Dave added a pair of recessed mounting points to this design to keep the undercarriage and mounting hardware safe.

As sophisticated as our scanner and modeling software are, nothing quite beats installing our design on the vehicle itself. So, with the help of our waterjet, bender, and fabricator, we were able to bring this digital design to life. While our prototype may not be pretty and might not be the final material choice, it still allows Dave to check the fitment of this skid plate on our M3 and make updates to the design without having to wait for an entire production run.

Nothing’s perfect. Even the reigning lord of the executive sports compact segment has room to improve. The M3 and M4 may dominate their competition, but the soft underbelly leaves these beats with a crucial weakness. With our plans and prototypes complete, all we have left is our skid plate production, so make sure that you stay tuned for the first look at our complete plate coming soon!

Thanks for Reading!

-Nick