Understanding the Advantages of Dedicated EV Platforms Over ICE Modifications

What exactly is a car platform? It serves as the structural foundation of a vehicle. Its design and specifications influence the car's rigidity, suspension, interior space, as well as engineering decisions like motor and transmission selection. Legacy automotive manufacturers, who until recently primarily produced internal combustion engine (ICE) vehicles, now face a crucial decision: should they discard their existing platforms in favor of dedicated electric vehicle (EV) platforms, or should they modify their current platforms to accommodate electric drivetrains?

The industry lacks a unanimous consensus regarding this issue. Some manufacturers choose to adapt existing ICE platforms, while others venture into creating entirely new dedicated platforms from scratch. There are also those that implement a hybrid approach, utilizing both methods across different models. Let's evaluate the benefits of each strategy.

Modified ICE Platforms

In designing an ICE platform, manufacturers typically plan for the long term. To support electric vehicles, engineers need to anticipate future requirements in their designs. For instance, consider the MQB platform from the Volkswagen Group, engineered to accommodate various propulsion methods, including gasoline, diesel, compressed natural gas, plug-in hybrids, and fully electric drivetrains. While this approach provides production flexibility, the platform remains primarily geared towards ICE vehicles.

Another example includes BMW’s CLAR and FAAR platforms, both originally designed for ICE vehicles but adaptable for EVs as well. The majority of traditional ICE vehicles follow a “front-engine” layout. Consequently, if the engine is placed transversely in the vehicle alongside the gearbox, power delivery occurs through the front axle, which will affect any electric vehicle derived from that ICE platform.

Typically, ICE platforms incorporate predictions for exhaust piping and potential all-wheel-drive hardware. When replacing these systems with batteries, manufacturers often face challenges in creating complex shapes, such as “H” or “T” designs, limiting the battery capacity and flexibility in offering various power options across the same model.

Moreover, existing ICE layouts often include a tunnel running beneath the rear passenger compartment, which can split the space and pose challenges in torque handling and optimize spatial use.

In contrast, this torque-handling disadvantage is less significant on platforms designed for rear-wheel drive, such as BMW’s CLAR.

Dedicated platforms typically entail substantial research and development resources and require more time for development, which can result in higher vehicle costs and delayed market releases. Nonetheless, they present several long-term advantages that might justify the investment.

Firstly, let's discuss the physics involved. If you've ever experienced rapid acceleration in a high-performance car, you likely felt your back pressed against the seat, indicating a weight shift to the back of the vehicle. To fully capitalize on the significant torque produced by electric motors almost instantly—while minimizing traction loss—the torque must be directed to the rear axle.

This is why electric vehicles with a single motor usually drive the rear axle, enhancing the turning radius due to the absence of front driveshafts. Conversely, the Renault Megane E-Tech and Nissan Ariya are both front-wheel drive, despite being built on dedicated platforms (CMF-)—a decision driven by considerations for weight and space efficiency. By centralizing components in the front, the design reduces overall weight by approximately 100 kg, primarily through shortened piping and high-voltage cable lengths, while also optimizing trunk space.

Another key advantage of dedicated platforms is the simplified battery geometry, which can be arranged compactly between the axles, permitting various energy capacities by integrating additional modules into the battery pack. However, this “skateboard” configuration complicates the design of the rear suspension; in compact vehicles, multi-link fully independent suspensions with longitudinal links become impractical, necessitating the use of transverse links instead.

Regarding spatial efficiency, a dedicated platform supports a flat floor within the vehicle interior, extends the wheelbase, and reduces the needed space for the “engine compartment.” As a result, interior room in electric vehicles can rival that of larger cars.

However, since the main battery is positioned low in the vehicle, manufacturers often need to slightly raise the vehicle height. Thus, electric mobility favors SUVs and crossovers, which can pose challenges in terms of aerodynamics.

In constructing lower electric vehicles, such as sports coupes, manufacturers like Porsche and Audi implement the foot garage concept in models like the Taycan and E-Tron GT, creating a gap in the battery pack to provide extra space for rear passengers' feet.

Final Thoughts

It's clear that dedicated platforms offer numerous advantages over conventional modular ICE platforms. In essence, we can categorize these platforms into three broad types: the slower, yet efficient dedicated platform, the middle ground represented by modular ICE platforms with rear-wheel drive configurations, and the compromise model, which involves adapting front-wheel-drive ICE platforms. The following comparison table provides a quick overview of these different approaches.