Understanding the Forester's and XV’s Subaru Global Platform

TC Subaru, the authorized distributor of Subaru vehicles in Malaysia and subsidiary of the Motor Image Group, has today launched the all-new Subaru Forester.

The five-seater Forester starts from RM 139,788 to RM 159,788. All variants are powered by a 2.0-litre naturally aspirated direct injection four-cylinder ‘boxer’ engine, paired to a CVT-type automatic transmission driving all four wheels (active torque split symmetrical all-wheel drive).

• Forester 2.0i-L: RM 139,788
• Forester 2.0i-S: RM 149,788
• Forester 2.0i-S Eyesight: RM 159,788

Highlights of the all-new Forester include the EyeSight feature - similar to Honda’s Sensing, albeit executed in a simpler manner and with slightly less functions – as well as the Subaru Global Platform that underpins it.

While Honda’s Sensing uses both camera and radar, Subaru’s EyeSight uses a stereo camera-only setup. It does almost everything the Honda Sensing is capable off, except for Lane Keeping Assist and Low Speed Follow (adaptive cruise control with stop-go traffic capability).

This means that Subaru’s system will warn the driver if vehicle strays out of lane, but it doesn’t do any steering correction. The Forester’s adaptive cruise control also don’t work in stop-go traffic, but Forester models sold in certain markets equipped with the more advanced EyeSight Touring Assist can do all of the above.

The Subaru Global Platform is something that adds a lot of value to the car, but it can be difficult to explain or demonstrate to the customer.

What is a platform?

There is no specific definition of what a platform is, although it is generally accepted that a platform include (but not limited to) mounting points for key components like engine, suspension and seat belts.

You may imagine a platform to be like main pillars of building. You may tear down a building for renovation, and remodel the building into another style, so long as the pillars and supporting beams can support the new design.

However unlike pillars on buildings, some platforms can be stretched or shortened – we call this modular platforms.

Generally, a platform’s hard points are the distance between the engine bulkhead and front suspension mount, as well as location of seatbelt mounts on the B- and C-pillar, and rear suspension mounting points.

How platform affects handling, comfort and safety

Handling is defined by the delay in response between the driver’s steering input and the car’s actual change in direction. A good handling car responds like an extension of a driver’s hands and feet - immediate and predictable. 

In order for a car to handle well, the platform needs to be rigid so it doesn’t flex when the car turns or go over uneven road surfaces. While this might sound hard to believe, every physical structure – even tall buildings or bridges - flexes and distorts when subjected to an external force.

Some amount of flexing is necessary, but too much flex is not good. For example, all bridges are designed to flex every time a heavy vehicle drives over it. If it doesn’t flex, the forces acting on the structure might break or shatter a bridge.

It’s the same with a car’s body structure. Some amount of flex is necessary but too much flex will cause the steering and suspension structure to move too much, causing further delay in a car’s ability to react to new steering input, thus resulting in poor handling.

While rigidity is good for handling and safety, a very rigid structure with poorly designed damping points will allow too much vibration - when driving over rough roads for example - to be transmitted into the car’s interior.

A good platform (image above) will control the vibration, diverting it away from the cabin or distributing the vibration/forces over a wider area so it becomes less intense.

Together with Subaru’s ring-shaped reinforcement around the cabin, Subaru’s Global Platform solves this problem by having multiple, gentle curving paths for energy to dissipate around the cabin. This not only makes the car more comfortable, but also safer.

The highly rigid platform also ensures that key points of the vehicle’s chassis – do not flex even when subjected to high speeds or sharp corners.