Model S: Designing the Perfect Endurance Athlete
Q&A with Tesla Chief Designer Franz von Holzhausen and Model S Program Director Jerome Guillen
Interest in Model S is running high as it enters the Beta phase of development. We recently put out a call to Tesla owners and fans to ask questions about the car’s design via Twitter, Facebook, and the Tesla Forums. Below, Chief Designer Franz von Holzhausen and Model S Program Director Jerome Guillen take on a mash-up of queries about anything and everything design-related – right down to the door handles.
How would you describe your philosophy and approach when you first designed Model S?
Franz: The physique of an athlete is a finely tuned machine, developed to accomplish a specific goal. Like a world-class endurance athlete, Model S was designed to be the epitome of efficiency. One of the amazing opportunities I had when I came to Tesla was to start with a clean sheet of paper with Model S. With little constraint, I had the freedom to create the long, lean musculature of an athlete embodying grace and performance.
How do you translate inspiration into a real product?
Franz: A vehicle’s design is a living sculpture, a fluid object. We spend hours defining and redefining the surfaces, tension, line, and weight balance using a clay sculpture. Just like that endurance athlete honing her body day in and day out, we continuously sculpted the shape for better performance.
Our goal is to modernize the design of the classic sedan silhouette and make it unique to Tesla. To do this, we streamlined the greenhouse (the area enclosed by windows) and stretched it to feel lower and leaner than usual. We wanted it to express speed and motion, even when at rest. I think we’ve accomplished that goal.
It is clear the design prototype was a "labor of love." Can you speak to the changes you’ve made to the prototype since then?
Franz: Most traditional automotive prototypes look very little like the cars that make it on the road. In previous jobs at other car companies, I’d hand off a design to production and my input ended. Not so at Tesla.
Tesla’s design team created the design prototype with fundamental understanding of the realities of production. We forged a tight relationship with the vehicle and powertrain engineering teams to maintain tight communication throughout Model S development. For example, if you look at the Model S Alpha from the side, and compare that to the design prototype, the centerline (the curve from the hood to the rear of the car), has not changed. From the outset, we designed the exterior to contain the right interior volume. Every millimeter of the car has been considered by the design and engineering teams. This close teamwork is unique to Tesla.
What were the biggest challenges in designing Model S?
Franz: The freedom of having a blank slate was also my biggest challenge. In addition to defining Model S, Tesla’s brand is still evolving. We’re just starting to create the design language that defines “Tesla” as a brand of vehicles. It’s incredibly exciting.
If you had to pick one aspect of the vehicle that is truly a step forward for the automotive industry, what would it be?
Franz: The architecture. Model S is a revolutionary vehicle: not only due to its electric propulsion, but also in that its engineering and design go hand-in-hand. We have designed Model S from the ground up as an EV. The unique powertrain integration allows for an unprecedented package that is both rigid and incredibly safe. We set out to redefine the electric car, but with room for seven passengers and more functional storage space than any sedan on the market, Model S will set a new bar for the premium sedan as well.
Are you keeping the awesome door handles?
Franz: Yes! Door handles will be flush to the body of the car on every Model S. The handles are people’s first point of contact with the car. They should feel solid and inspire confidence, but they should also lend to the aerodynamics of the vehicle. That’s why I wanted the handles to be more of an accent, appearing when needed. As planned, they will only present themselves when passengers approach the car. Making the handles flush to the body improves airflow down the body’s sides, reducing the drag coefficient and extending range.
I like the fenders and how they wrap closely around the wheels. Will this be the same on the final production version?
Franz: Yes. We paid close attention to balance and stance as we developed Model S. We put quite a bit of effort into the interaction of the wheel and the body. We focused on creating the impression that the wheels are supporting the body, flush and tight to the openings with minimal gaps. It was really important to me that the car didn’t feel over-bodied to the wheels or overweight.
I know the Roadster uses carbon fiber composites for aesthetic accents and the body panels, but what about the future Tesla cars?
Franz: For limited or low volume production cars like the Roadster, carbon fiber is a great material to reduce weight. It’s not a solution for higher volume production due to cost and manufacturing time. For Model S, we are using aluminum for the body panels and chassis. Aluminum is as strong as steel but lighter in weight, and has similar manufacturing capabilities. Lighter weight translates directly to efficiency.
The prototype cars had fantastic-looking light-pipe rear running lights (the lights that are illuminated while not braking). Will the final design retain distinctive rear lighting effects?
Franz: Absolutely. The lighting on the Model S helps produce a distinctive look for Tesla. The “wow” factor should be just as powerful looking head-on in the bright sunlight as it is at night in a rear-view mirror.
Where is the charge port located?
Franz: The charge port is located toward the rear of the car, on the driver’s side. The majority of charging happens at home so this is the most functional location. Similar to the door handles, the charge port door hides when not in use. It was important to me to make charging a unique experience. You’ll see on the Beta vehicles, the charge port looks nothing like a traditional fuel door.
When will options be announced?
Jerome: Later this year.
Will Model S have a spare wheel/tire and where will it be located?
Jerome: To maximize the sporty, premium feel as well as range, Model S will not carry a spare wheel (except in markets where it is mandated by law).
Will a towbar, tow hitch, or roof racks be options on Model S?
Jerome: We are not planning to offer a tow bar or hitch; Model S is a performance sedan. The standard roof will accommodate roof racks that mount on door frames. That said, because the Model S will have nearly twice the storage capacity of other sedans in its class, we suggest using the front or rear cargo areas to carry your gear.
Can you comment on the vehicle’s ground clearance? Will the doors be able to clear a curb if I park too close?
Jerome: We have optimized the car for best-in-class aerodynamic performance to maximize the range (which also happens to make the car look gorgeous). This task requires as low a ground clearance as possible. But we also want Model S to deliver an amazing experience on normal roads and in normal parking lots. The Alphas deliver an amazing daily driver experience even when driving over speed bumps or through steep parking lot entrances.
Will the door windows on the production Model S be "frameless"?
Jerome: Yes! We will have four frameless doors on Model S. The windows will have “short drop” (windows that roll down slightly when a door is opened) functionality, which is common on premium vehicles with frameless doors.
What options will be available for hot weather?
Jerome: The Model S is designed to excel in all climates. We have the most advanced cooling system to make sure that the drive unit and the battery stay at an optimal temperature for performance and durability, and we designed our advanced HVAC system that uses an environmentally-friendly refrigerant gas. Additionally, we have superior glass on Model S where needed: the Panoramic Roof, for example, will have an innovative infrared coating, reducing incoming solar load to 20% (for similar sedans, this is typically 50%).
Has the car been designed for easy servicing and repairs by qualified personnel when something breaks?
Jerome: Of course! We are always growing our service organization. Our service locations are also hubs for the Tesla Rangers, mobile technicians who make house calls. Making service easy for owners starts by reducing the frequency of service. Model S has far fewer moving parts than internal combustion vehicles. Additionally, the car can be diagnosed and even repaired over a wireless or 3G signal.
Will there be an online Design Studio for the Model S similar to the Design Studio for the Roadster?
Franz: Yes, everything we learned from the Roadster Design Studio will be featured in the Model S Design Studio. The new platform will give you the chance to develop your very own Model S.
When will reservation holders get to see a Model S Beta in person?
Jerome: We have started assembling the Beta vehicles. While most Betas are intended for testing to prepare for production, a few are earmarked for visits to North American Tesla stores later this year. Reservations holders will be the first to hear about them.