The Chevrolet Volt, a plug-in hybrid touted as a high-tech image-changer for General Motors, recently passed a milestone when Andrew Farah, the car's chief engineer, drove the first prototype of the production version. He said GM engineers are working to reduce road and wind noise and tweak the sound of the drivetrain.
Farah spoke with Staff Reporter Richard Truett about the Volt's progress toward its November 2010 production date.
What is it like when you step on the accelerator with the engine running? Since it is not connected to the wheels, it must be a strange sensation.
You get immediate response from the foot pedal -- I am reluctant to call it the throttle because it is not, in the traditional sense. But you get immediate response because the Volt is always driven electrically. You don't even notice the difference there. The gasoline engine's rpms then follow.
The engine, not being directly connected to the foot, is one of the things we continue to tune. We don't want it to be discomforting to people. There is an expectation of what happens when you put your accelerator to the floor in the way the car sounds and feels. We've got the feel. We've got the feel of a sports car. The sound part and the way the engine plays into that perception is one of the areas we have to work on.
How is the noise, vibration and harshness?
Realistically, we still have some work to do. During my ride, I was very pleased with the first steps. It was great.
We are using a liquid applied sound deadener that allows us to put sound where we want it to be. We have packaged-in sound suppression items in the front of the dash and glass. We are going to make final calls on how much of that to execute.
But the decisions have been made on how you want the car to sound, right?
We want the EV portion of the ride to be exactly that. We are not looking for the wind noise to be objectionable. Our biggest concerns are wind noise and road noise, mostly conducted road noise. Those are the things we are shooting for.
Do we want it to be Cadillac library quiet? We aren't sure we want it to be that quiet. It might be disconcerting.
You've got the powertrain in the right chassis and with the right body and interior. How did the packaging of the car work out?
Well, first everyone likes to say that everything can be done on the computer. It can't.
We did have some interference with the instrument panel that we didn't expect. It was a minor one, but still unexpected. We all kind of scratched our heads and said, "How did that happen?" We made a little change, and off we went.
Here's a car with a full electric powertrain and a gasoline engine. Does it feel heavy?
Here's the thing to remember: When you put the battery in, it actually lowers the center of gravity of the car. There are a thousand reasons why heavy is bad, but a few why it is good. And so we are getting those advantages of the good heavy, and the disadvantages we are managing. When it comes to the ride and handling, I won't tell you that there are no detriments, but I will tell you that we are taking the best of the advantages.
What testing still needs to be done?
This is really just the beginning of all the final tuning. We are at the 50 percent point. Fundamentally, we've got everything directionally correct, but now we've got all the tuning yet to do.