DETROIT — Chrysler LLC has begun an emergency overhaul of its new mid-sized sedans, the much-criticized Chrysler Sebring and Dodge Avenger.

Sales of the two cars, which share a platform, have been hugely disappointing. A team being assembled for the crash program, called Project D, will concentrate on redesigning the interiors, according to a supplier executive familiar with the program.

The team will include some senior managers and directors who took recent buyouts and are returning as contract employees, the source said.

Critics have blasted the sedans for the cheap plastic look and feel of their interiors.

The Sebring debuted in the fall of 2006, and the Avenger was launched in January. Both have struggled to find retail buyers.

Meanwhile, CEO Bob Nardelli is adding firepower to Chrysler's purchasing department in an effort to reduce costs.

Nardelli, former chairman of Home Depot, has brought the retailer's former purchasing boss, John Campi, to Chrysler as an adviser.

Simon Boag, Chrysler's purchasing chief, said he is working closely with Campi. Before going to Home Depot, Campi worked at DuPont and General Electric and is regarded as an expert in cost control and global supply chain management.

Nardelli is caught in a cash crunch as he labors to fix Chrysler. Cerberus Capital Management LP, which owns 80.1 percent of Chrysler, has a cushion of about $10 billion in cash. Nardelli is in a race against time to improve Chrysler's products while bringing costs down and increasing profit margins.

Cerberus borrowed the $10 billion from five major banks to fund Chrysler's cash needs during its turnaround. Collateral for the loan is all of Chrysler's assets, including trademarks, factories, real estate, receivables and inventory.

Those banks planned to syndicate those loans with other lenders. But the plans have been postponed twice because of lack of investor interest. Analysts say that won't hurt Chrysler operations directly but could make it more difficult for Cerberus to raise additional funds for Chrysler in the future.