By David Goldman, CNNMoney.com staff writer

Last Updated: September 30, 2009: 5:18 PM ET

NEW YORK (CNNMoney.com) — Car dealership operator Penske Automotive Group announced on Wednesday that it has cancelled plans to acquire General Motors’ Saturn unit. As a result, GM said it will wind down the brand and dealer network.

The announcement comes nearly four months after Penske agreed to buy the rights to the 19-year old brand from GM when the automaker was in bankruptcy.

As part of the deal, GM would have continued making Saturn’s three highest-selling models: the Aura sedan, and the Vue and Outlook cross-over SUVs, for the rest of this year and next. Penske, an auto distributor but not a manufacturer, would have sold the cars for GM. In 2011, Penske said it would find another third-party manufacturer to make new Saturns.

But negotiations with another manufacturer fell through after an agreement was rejected by the unnamed manufacturer’s board, according to Penske.

“Without that agreement, the company has determined that the risks and uncertainties related to the availability of future products prohibit the company from moving forward with this transaction,” the company said in a statement.

As a result, GM said it would begin to wind down the brand and its roughly 350 dealerships nationwide.

Penske’s deal with GM, which was expected to be completed in October, would have saved more than 13,000 jobs at Saturn.

GM called the news “very disappointing.” The automaker said Saturn owners will still be able to have their cars serviced at GM dealerships after Saturn is shuttered.

A spokesman for GM said the broken negotiations with Penske would have “no anticipated impact on plants or related losses.”

Penske (PAG, Fortune 500) is owned by former race car driver Roger Penske, who owns NASCAR and IndyCar racing teams and distributes Daimler AG’s Smart cars in the United States.

– CNN’s Ekin Middleton contributed to this story