General Motors, Chrysler and Ford have been developing and testing six-way seat harnesses, head and neck restraint systems, safer seats and, most important, cars with front ends that protect drivers better in crashes.

Car safety is at the center of the NASCAR investigation of Earnhardt's fatal wreck, the Orlando Sentinel reported Friday, citing sources close to the investigation who spoke on condition of anonymity.

The investigation found cars don't have enough crush resistance in the front ends to adequately protect drivers in crashes, the newspaper said. The investigation also will not blame Earnhardt's death on a broken seat belt, the Sentinel reported, despite NASCAR's earlier assertion that it played a role.

NASCAR would not comment on the Sentinel article. The results of the investigation are to be released Aug. 21 in Atlanta.

''Speculation prior to that time serves no useful purpose,'' NASCAR said in a statement.

The manufacturers have been involved in the Earnhardt investigation, but emphasize they have not yet seen the results of the study by some 54 safety experts.

The automakers have, however, been working with NASCAR on driver safety since before Earnhardt's deadly crash at the Feb. 18 Daytona 500, and even before the deaths last year of drivers Adam Petty, Kenny Irwin Jr. and Tony Roper.

Earnhardt, Petty and Irwin died from skull fractures caused by a whipping motion of the head at the moment of impact. Roper died from massive head injuries.

The consensus among automakers appears to be that the focus on driver safety should be inside the cockpit, not on the outside of the car.

Since Earnhardt's death, the use of the HANS and similar devices has tripled among Winston Cup drivers, with 33 of the 43 starters last month in the Pepsi 400 at Daytona wearing some form of head and neck restraint.

The manufacturers also are looking at the rigidity of the NASCAR chassis, particularly the front of the cars.

There has been speculation that the fronts of stock cars are too rigid and pass on too much energy to the driver in crashes like Earnhardt's. The Earnhardt, Petty and Irwin wrecks were all at angles involving at least part of the front of the car.

One key point in NASCAR's findings is that cars might have to be redesigned using energy-absorbent bumpers and aluminum-foam ''crush box'' technology, the Sentinel reported.

One group is working on an energy absorbent front-end system called the ''Humpy Bumper,'' named for Lowes Motor Speedway president H.A. ''Humpy'' Wheeler, who is involved in its development.