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  • Interview: Jill Dennis, Lead Development Engineer, Chevy Equinox and GMC Terrain

Interview: Jill Dennis, Lead Development Engineer, Chevy Equinox and GMC Terrain

Interview

Gary Witzenburg
Jul 9, 2018
Photographers: Courtesy of GM
Jill Dennis grew up in Clarkston, Michigan, north of Detroit, and earned her mechanical engineering degree from the University of Michigan in Ann Arbor. She worked as an intern for General Motors for three consecutive summers, then hired into Pontiac Motor Division as an experimental engineer in 1983. "I worked in the lab doing tests and at times analyzing data at the Milford Proving Grounds," she says. "My dad was an engineer at Pontiac and a fix-it guy, and I was interested in fixing things. I learned about mechanical things and how they worked by assisting my dad working on lawnmowers, snowmobiles, and minibikes."
Over time, Jill moved into transmissions and axles as a validation engineer, then became a design engineer, and moved to vehicle development on the first front-drive Pontiac Grand Prix at the Proving Grounds. Promoted to validation manager on the GM "W cars" (Pontiac Grand Prix, Oldsmobile Cutlass, and Buick Regal), Jill was responsible for vehicle and component testing in the labs, at the Proving Grounds, and at suppliers. Next, she moved to GM’s Quality Group, then back to Milford as vehicle performance manager on the GMT 360 midsize SUV program (Chevrolet Trailblazer, GMC Envoy, Oldsmobile Bravada, Buick Rainer). She was then appointed to this position in 2006.
Photo 2/10   |   Interview Jill Dennis
Truck Trend: What were this program’s toughest challenges?
Jill Dennis: Most of this program. When we decided on the size and shape and what it would be, looking at all the imperatives: mass, safety, driveability, and a lot that they wanted it to do. Some were conflicting requirements that had to be balanced and optimized, and we don’t get a lot of time these days to optimize new products. Then they told us they wanted to get 400 pounds out of it.
TT: Among your top priorities, fuel efficiency and performance can conflict.
JD: Yes, and crashworthiness. It’s easy to build a tank that weighs 10,000 pounds, but how do you build something that is great for crash in all directions—front, rear, and side—and weigh less? You don’t take a vehicle design that you did years ago and just make it smaller. You have to think of things differently and look strategically at where you’re going to use premium materials, high-strength steel, and adhesives.
TT: Were the fuel-economy targets difficult to hit?
JD: Yes. As you know, the regulations are very aggressive, so we needed to develop technologies such as start-stop and all-wheel-drive disconnect. There is a rollout of what every program has to contribute to meet the company target, and this is a high-volume program, so it would really affect a lot of others if we didn’t get there.
Photo 3/10   |   Interview Jill Dennis Equinox Side View
TT: Was your mass target non-negotiable?
JD: Right. It was to get it into lower test-weight classes. Once you’re in a certain test-weight class, you can analyze and determine what your fuel economy will be.
TT: And you had three very different powertrains.
JD: Yep. You're packaging for all three and don’t want to add width or mass to accommodate one that you don’t need for another. The diesel and 2.0L (with its nine-speed automatic) are heavy, so you don’t want to design something to support them, then have to use the same part for the 1.5L, because that is your low-mass solution. And the 2L had to fit in the same space as the 1.5. We optimized for the 1.5, and then added where we had to for the 2.0L and diesel.
TT: The balance of ride and handling also can fight each other.
JD: Yes, especially with the front and rear cradles solid-mounted to the body. There is very little rubber in this vehicle. You don’t have cradle mounts to help isolate, and there are not a lot of bushings. You pretty much have to do it with the control-arm and trailing-link bushings.
TT: Another challenge was quieting the diesel.
JD: Yes. We used a lighter-weight dissipative system, but we had to go to a denser material.
Photo 4/10   |   Interview Jill Dennis Equinox Drive
TT: While keeping it under your cost target.
JD: You have to know what to fight for. If there is something that I say, “We have to have this, I don’t care if it costs whatever,” you have to know when to lay down in front of the bus for certain things that you know are most beneficial to the customer, and then give in on others.
TT: What is your product philosophy?
JD: Knowing what customers want and need and how to provide it to them, and finding the best engineering solutions to meet cost, manufacturing, and design imperatives.
TT: How do you know what customers want and need?
JD: By looking at marketing surveys, going through data on what people like and don’t like about the previous generation, trying to correct those things, and then bringing in new features and technologies that should delight them. We look at trends of what people are using in other products and conveniences that you can put into the vehicle. Storage is important, for example, and being able to use Wi-Fi in the vehicle.
Photo 5/10   |   Interview Jill Dennis Equinox Rear
TT: And your leadership philosophy?
JD: My number-one goal is to make people accountable. My job is setting priorities for what they are working on, and if they have a problem, I get involved to provide support and help in removing roadblocks. I don’t like to micromanage, but I like to give people deadlines and make them accountable for producing, so the engineers can be creative without someone looking over their shoulders. I am here as a resource to them, and I expect them to get their jobs done and let me know if things are not going well.
TT: Where do you believe you have your competitors beaten with this vehicle?
JD: On fuel economy, we are right up there with the best. I think our ride and handling balance is better, and the way we integrate and give our customers the noise performance, the acceleration, the utility, and functionality. I think we have the whole package compared to our primary competitors. And I think we have some of the best-looking vehicles.

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