[Mike’s preamble: This is part two and the conclusion of Mr. Ruzzin’s fascinating look into the design and development process of General Motors’ X-Car. If you have not yet read part one, please do so to gain pertinent background before proceeding by following this link: Guest Post: Designing the X-Car, Part 1. As stated in the first part, I have not included any photos but will add them once procured at a later date.

Mr. Ruzzin’s words start below.]

The design process
Automotive design follows the same process that is used in the art and industrial design world for creating a product. First the intellectual focus, and product definition and criteria are developed. Next come some quick sketches which are followed by more refined sketches, scale models, a full-size seating buck to experience utility and space, and finally a full-size model to completely visualize the product solution. Finally, detail it and send it off in the form of numerical data for production in high volume.

In the case of a car, the interior is done in concert with the exterior. The interior / exterior design process is an iterative one that impacts both simultaneously, as they affect each other. It should be clearly understood that all of these steps are designed to refine and develop a solution, the iterations advance as decisions are made. Finally, after each step a statement is made in that idiom and it displays the necessary progress, opening the door to the next step.

This process was typical of that used throughout Design Staff. Also, within any design organization there is a design culture, an aesthetic that has required boundaries that reflect the requirements of the functional solutions that are needed. The culture is an unspoken language that reflects the way things are done by that group of designers.

A Quantum Leap
Our group was very tuned in to the small fuel efficient products that were present in the European and Japanese markets. Our culture was different than that of the rest of the Design building and we started comparing our designs to small foreign products, not those that were our corporate or national heritage. As we worked and created the TASC Program products this became increasingly apparent. What we were doing, the clay models and seating bucks, became the visible evidence that the corporate portfolio must change rapidly. We were able to demonstrate a new level of fuel economy, interior space and luggage capacity all packaged as much smaller cars than we had currently in the showrooms.

The advancement of the work is a learning process that is a race against time. Design time is always limited, the faster and further you go the better the solution will be.

Shaping the car
The design culture in the International Studio was very much in tune with what we saw and admired in many foreign products. We were confronting some of the same proportional design problems. What is more significant is that the aerodynamic and functional solutions were in sync. That left us with the actual aesthetic, or design solutions to achieve.

The release model started with a semi-fastback but Bill Mitchell made it very clear early on that a pure fastback profile was what he wanted. A high tail that was defined by our aero studies worked very well with the desired luggage capacity. We were able to achieve over 13 cubic feet of luggage capacity, the same as a big Buick C-Car but in a more desirable cubic proportion in a much smaller car, two sizes down in scale.

We started with a fairly flat body side but moved on to a more rounded side section when safety criteria was added, door beams and a new lightweight tape driven window lift mechanism.

Our original front carried the new large single headlamp in a rectangular shape and an egg-crate grill which was common for Chevrolets at the time. The front profile was rounded in section to match the body side.

In the rear of the X-Car a wide tailamp unit, with three lamps per side and an included wrap around side marker, was integrated into the shape. A body color panel was below the tailamp to raise them visually above the rear bumper. This looked great but conflicted with the desire for a low load height for the hatchback. Shortly after, a facelift on the Chevette incorporated our original rear end design.

The wind tunnel tests at Lockheed focused on the A-Pillar section, drip molding and outside rear view mirror shape and location. A lot of aero work was done around those elements as well as optimizing the overall shape in profile and plan view. Body attitude to the ground line and rocker locations as well as ride height were critical to the aero success. The tests proved that the studios desire for a small drip molding and a smooth pillar was the lowest drag achievable. For the first time a serious effort was made to reduce wind noise and to control rainwater as it streamed over the side glass between the drivers eye and the rear view mirror. This was new science that was developed and used for the first time on a GM product.

Continue to page 2, below.

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