The Tech Corner: Question and Answer

May 15,1999

Welcome to the newest part of our fledging website. This part of Motion Magazine will actually be shared by the regular tidbits section, however this special Q and A / TechCorner will appear every so often to keep you informed and up-to-date with new developments or pressing questions from the automotive world.
If you want any question answered by our tech guys, then send your email to [email protected]. Watch this space for their answer!

Q: When new car models are introduced, I commonly hear a reference to car platforms and certain cars sharing platforms. What exactly are platforms and when is a car considered having an all-new platform?

A: Platforms are the basic structure of a car’s body. Cars have two main types of structure: a monocoque chassis or a body-on-frame construction.

As the name implies, monocoque (French-derived term meaning single shell) chassis do not have a separate frame. The body panels, floorpan and roof structure are welded or bonded together to form one structure. Almost all modern cars have a monocoque, usually welded together from stamped steel panels. The McLaren F1 has a monocoque structure bonded together from carbon fibre.

There are some notable exceptions, though, like Audi A8 and 360 Modena, which use body-on-frame construction.

Now the exact definition varies, but the platform usually refers to the car’s basic floor section. This floor section includes mounting points for the engine, suspension, hydraulic lines for the brakes, and tunnels for the electric wiring harness.

Manufacturers are able to save enormous sums by having two or more cars derived from the same platform. The development of one completely new platform for mass production might cost a carmaker more than a billion dollars.

When two or more models are based on the same platform, they can share major parts like engines and suspension bits. This results in huge savings in design and tooling costs for the manufacturer and its suppliers.

Platforms can be altered by lengthening or shortening the wheelbase and/or overhangs, while retaining the major mounting points for engine, suspension parts and other components. It’s relatively inexpensive to lengthen or shorten parts like hoses and tubing to fit the new wheelbase.

Also, when the time comes to introduce a new model, manufacturers might save money by changing the car’s appearance without altering the platform. Until recently, Japanese makers followed the 2-4-8 model system. This means a car will receive a facelift 2 years after its introduction, major body panel changes (but same platform) after 4 years, and completely new platform after 8 years. Thus “all-new” is true only every 8 years or so, when the platform itself changes. Some Japanese makers now follow a longer cycle due to economic constraints.

Examples of some cars that have the same platform but are quite different in appearance and purpose:

Audi A4 and Volkswagen Passat
Ford Mondeo / Countour and Cougar, future Jaguar X400
Honda Civic and CRV
Honda Accord and Odyssey
Jaguar S-type and Lincoln SS
Mitsubishi Carisma (available in Europe and Japan) and Volvo S40
Opel Vectra and Saab 9-5
Volkswagen Golf and Jetta, Audi A3, Seat Toledo and Skoda Octavia

As you can see, Volkswagen has been exploiting the advantages of basing multiple models on the same platform.

Note: the Ssangyong Musso and Mercedes-Benz ML 320 are NOT an example of shared platform.

Text By Redline | Photos From MOTION Magazine and Car Chart

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