Regulators at the National Highway Traffic Safety Administration (NHTSA) are siding with the Ford Motor Co., ruling that claims by the consumer group Public Citizen that some flex-fuel Ford and Mercury vehicles are defective are not substantiated.

Public Citizen asked NHTSA in October 2006 to investigate Ford flex-fuel claims for several models but NHTSA rejected the petition.

Headed by former NHTSA Administrator Joan Claybrook, Public Citizen claimed that 2003-05 Ford Taurus and Mercury Sable vehicles do not perform up to standards when fueled with E85 which is composed of 85 percent ethanol and 15 percent gasoline.

Public Citizen argued that the engine stalling in the Fords was a safety hazard.

The consumer group asked that NHTSA revoke the extra fuel economy credits Ford received for building 228,000 of the cars.

In justifying the decision, NHTSA said repairs recommended by Ford fix the performance problems in the vehicles.

NHTSA said that while the Ford models encountered a problem starting when using E85, stalling in the vehicles was rare.

NHTSA reported no crashes related to the complaints and said the decision does not prevent the agency from taking action if new evidence of a safety defect emerges.