Retired GM chief Dan Akerson likens rumored Apple car program to 'trying to cough up a hairball'

"I think somebody is kind of trying to cough up a hairball here," Akerson told Bloomberg. "If I were an Apple shareholder, I wouldn't be very happy. I would be highly suspect of the long-term prospect of getting into a low-margin, heavy-manufacturing business."

GM's gross margin for the fourth quarter of 2014 was just over 11 percent — compared to nearly 40 percent for Apple - but Akerson was even more harsh in his assessment of Apple's manufacturing expertise.

"[Apple] better think carefully if they want to get into the hard-core manufacturing," he added. "We take steel, raw steel, and turn it into car. They have no idea what they're getting into if they get into that."

Akerson's comments are somewhat bizarre, given Apple's reputation for diving deeply into the development of materials and processes used to manufacture its devices. The forthcoming Apple Watch Sport, for example, uses ion-strengthened glass thought to have been developed in-house.

GM is no longer a vertically-integrated company, either. Much of the "raw steel" the automaker turns "into car" is supplied by European materials giant ArcelorMittal.

The auto industry has been aflutter since rumors of an "iCar" began to gather steam earlier this month. Apple was outed as the operator of a fleet of sensor-laden minivans that have been crisscrossing the country in recent months, a finding which sparked two separate reports of an early-stage Apple vehicle development program.

Apple spun up a "top secret research lab" for the project last year, the Financial Times said, kicking off the free-for-all. Design czar Jony Ive is believed to have personally recruited automotive executives, and the company is known to have offered massive bonuses and substantial pay raises to employees of electric carmaker Tesla.

The Wall Street Journal weighed in later, claiming that Apple CEO Tim Cook gave the go-ahead for iPod and iPhone designer Steve Zadesky to assemble as many as 1,000 workers to make an electric car. Zadesky's group is though to be researching "robotics, metals and materials consistent with automobile manufacturing."