The report on the complaints notes that the primary problem is that too much brake pedal pressure is required to stop the car, and that the problem is worse when the engine is cold, reports Automotive News. The problem reportedly only affects cars with the 2.0L turbocharged engines - which are only available in the 260hp Solstice GXP and Sky Red Line. The regular Solstice and Sky share a 2.4L naturally aspirated engine producing 173hp.
In December of last year, GM issued a technical service bulletin on the brake control units detailing a problem that could be related. The system that boosts brake pressure when the car isn't providing adequate vacuum - like when it is cold - may need to be recalibrated. The NHTSA investigation is only preliminary at this stage, however, so any conclusions about the final result at this point would be premature.
If a problem is found, however, the investigation could lead to a safety recall to have the problematic brake systems serviced or replaced.