Action Sports with Leigh Roche

A Chevrolet Cobalt involved in a 2010 fatal crash.

NEW YORK (CNNMoney)

The National Highway Traffic Safety Administration should have known that the cars needed to be taken off the road years before the 2014 recall, according to a report from the staff of the House Energy and Commerce committee.

The flawed ignition system caused the cars to shut off while driving and also disabled safety features such as the air bag and anti-lock brakes.

"NHTSA ...lacked the focus and rigor expected of a federal safety regulator," said the report. "The agency's repeated failure to identify, let alone explore, the potential defect theory related to the ignition switch — even after it was spelled out in a report the agency commissioned — is inexcusable."

The report repeated criticizes NHTSA staff for failing to understand how the cars' safety systems worked, and how they failed.

The agency disputed the report, saying its investigators were very aggressive in trying to find out the cause of the problems with the cars but that GM employees hid information from the agency. GM has already agreed to pay the maximum allowable $35 million fine to the agency for its conduct in this case.

"This report ignores the role that GM played in hiding information from NHTSA. In addition, many of the issues identified in the report have already been identified and addressed by NHTSA," said the agency in a statement.

Related: Ten years of guilt over GM fatal crash

GM has admitted that its employees were wrong to not order the recall. The carmaker released a report the described that as a "fundamental failure" by the company and has initiate a program to compensate victims.

The House report says the automaker bears "significant responsibility" for the "tragic failure to identify and remedy this defect."

But it also said NHTSA is "an agency struggling to keep pace with the industry it is responsible for overseeing," and one which "does not hold itself to the same standard of accountability as those it regulates."

The report referred to the agency's habit of deflecting blame as "the NHTSA shrug."

NHTSA acting director, David Friedman is due to appear before a Senate subcommittee looking at auto safety regulation later on Tuesday.

First Published: September 16, 2014: 12:45 PM ET...