The Chevy Volt is as much a software engineering accomplishment as it was a mechanical engineering challenge, according to General Motors.

General Motors today plans to bring the Chevy Volt to IBM's Raleigh, N.C., offices to show off the electric car and celebrate its partnership with IBM's software business in making the Volt.

With the Volt, GM aimed to not only break new ground in electric powertrains but it also decided to make a demonstrably high-tech car, complete with an Internet connection and smartphone-inspired in-car controls. To make that happen, software engineers took on one of the most sophisticated projects at GM, said Micky Bly, executive director of electrical systems, hybrids, electric vehicles and batteries at GM.

"We haven't done a vehicle this complex in the history of GM," Bly said on Friday. "The software--the control side--is what ties together (the mechanical components)...It's really the heart and soul of how the car performs."

GM used IBM development software to manage and simulate changes to the Volt&39's internal control systems.

The Volt, which GM has started manufacturing this fall, has a battery, motor to move the car, and gas engine to charge a generator. Making those mechanical components click are tens of millions of lines of code running on multiple controllers and processors embedded in the sedan.

The software coordinates the flow of energy and provides drivers feedback on how much charge is available, mileage, and when to charge--all critical to making drivers comfortable with electric-vehicle technology. Drivers can, for example, view charge status and schedule battery charging from a smartphone, thanks to a cellular network connection in the car.

The software also monitors the status of the individual 288 battery cells and modules as well as control the active cooling and heating system for the battery. This was important to ensuring the best energy efficiency and reliability, Bly said.

But the software engineering challenge was as much on the outside of the car as the inside, Bly said. The project was operating on a tight--and very public--deadline of 29 months and engineers needed an automated system, rather than just spreadsheets, for managing project requirements, software models, and changes.

Writing code is not really the challenge any more' it's managing the thousands of moving pieces in a project and using that material, such as requirements, code, and models, for future projects, Bly said.

"We're now at the point where software control strategies and controls are the gating factor of the vehicles we make. In the old days, it was sheet metal and other materials," he said. "We've really transformed the DNA of a vehicle."

GM used software from IBM's Rational division which is designed for managing complex software development projects in manufacturing industries, such as automotive and aerospace. Those tools, along with others, allowed GM to model and simulate potential changes quickly, Bly said.

IBM bought Telelogic in 2007 to boost its presence in these types of industries which increasingly need to focus on the software in their goods, said Meg Selfe, vice president of complex embedded systems at IBM Rational.

"Bringing all this new innovation is a big feat. What was transformational was how they handled the complexity," she said.