A consumer group claims it has uncovered indications of "widespread failure of automatic transissions in late-model General Motors vehicles... [indicating] a massive design problem," and has called upon the Federal Trade Commission to protect consumers affected.

In a letter to FTC Chairman Michael Pertschuk, made available to The Washington Post, the Center for Auto Safety contends that the GM Type 200 Turbo Hydramatic transmission, originally designed for the subcompact Chevette, has been placed in many larger GM cars - particularly late-model downsized models like the Chevrolet Malibu and Oldsmobile Cutlass.

The center claims that nearly 1000 consumers have filed complaints with it about the Type-200 transmission, and the problem is so serious that the automaker has begun a "secret warranty" program to reimburse anyone having the problem.

General Motors, in a statement issued last night, denied the reports of widespread failures of the automatic 200 transmissions, and added, "Further, there are no secret warranties at GM."

"All transmissions in GM vehicles are selected by our engineers for use in a particular vehicle," the statement said. "The weight of the car is matched to the power train, which includes the engine, transmission, and differential."

The world's largest automaker further contended that the 200 model was designed and tested for use in large vehicles, and had been modified for use in the Chevette. "Today," GM said "there are more than 20 different models in the 200 transmission family. These models are used across almost the entire GM passenger car product lines."

But in the letter to Pertschuk from the center's executive director, Clarence Ditlow, it was alleged that "several consumers, particularly owners of 1977 Chevrolet Impalas and Caprices, have confirmation from their dealers or other GM sources that the transmissions supplied with their cars are too light or too small.'

The letter quotes from written complaints from several consumers indicating that their transmissions had to be replaced early in the life of their cars, in some cases several times.

Center statistics revealed a sharp increase in complaints on full-size Chevrolet transmissions between the 1976 and 1977 models, when the 200-type transmission was put into use.