When it comes to exerting power in the auto parts business, Carl Icahn is certainly in the driver’s seat.

The investor, after this week buying the 680-location Aamco auto service center chain, has spent more than $2 billion in equity cobbling together a vertically integrated powerhouse with an eye on possibly taking it public, The Post has learned.

Icahn Automotive Group’s holdings now include parts retailer Pep Boys, parts distributor Auto Plus and the service center chains Just Brakes and Precision Tune Auto Care.

The investor also owns Federal-Mogul, an OEM and after-market parts supplier.

“The risk is small relative to the reward,” Icahn said, believing that creating the first true auto parts vertical will make the companies he is buying much more valuable.

Ultimately, an option is to debut IAG in an initial public offering, the investor said.

IAG paid about $125 million for Aamco — bringing to 1,900 the number of service centers it owns, a source estimates.

Also on the IAG drawing board are adding collision centers to Pep Boys locations.

Separately, Icahn owns 35 percent of Hertz Global Holdings and about 3 percent of ride-hailing company Lyft.

IAG services fleets including Hertz cars leased by Lyft drivers.

Meanwhile, the practice of monitoring bathroom brakes at IAG’s Auto Plus is no longer being done, Icahn said.

The investor said he was not aware of the practice, which his CEO Dan Ninivaggi said was not actually being enforced in the few locations where there were bathroom scanners, before the story ran in The Post.

Icahn said he is spending millions of dollars training mechanics on modern auto technology.