Chemical maker DuPont has started the auction of its car paint business, which could bring in more than $4 billion and has drawn early interest from a number of private equity firms, according to sources familiar with the matter.

DuPont's adviser on the deal, Credit Suisse Group, has sent out financial materials related to the unit to potentially interested parties, the sources said.

Reuters and other news organizations reported in October that DuPont was considering the sale of the unit, and several buyout firms have been preparing for the auction since late last year. The unit could also attract interest from other chemical companies.

Private equity firms find the unit especially attractive as they believe costs can easily be cut to make it more profitable, the sources said.

Still, it remains expensive for buyout firms to secure financing, which hurts returns and could makes buyout firms shy about offering top dollar for businesses.

Private equity firms Blackstone Group, Clayton Dubilier & Rice and Advent International are considering bids, sources familiar with the matter said.

Reuters reported in December that KKR & Co, Bain Capital, TPG Capital and Onex Corp had already made inquiries about the sale.

The performance coatings business primarily sells to Maaco and other auto paint refinishers. Ford Motor and General Motors are also key customers, though selling to so-called original equipment manufacturers is not as lucrative.

DuPont, Credit Suisse, Blackstone and CD&R declined to comment on the matter. Advent could not be immediately reached for comment.