On January 3, 2013, NHTSA received a letter (ODI No. 10487746) from Ms. Jessie A. Powell petitioning the agency to investigate drivability and braking concerns in the subject vehicle.The petition expressed two concerns: 1. The first software problem was when the vehicle shifted from battery to motor and caused such impact, I initially believed the vehicle had been struck in the rear.2. The next more alarming problem was NO BRAKES. The brake pedal traveled to the floor and a dashboard warning light flashed.This symptom occurred twice, leading to the vehicle being towed to the dealership, the second time in the dealership parking lot after diagnostics of the first incident.After a test drive and vehicle inspection, no actionable problem was found within the petitioner"s vehicle.The braking concern reported turned out to be normal vehicle operation.The petitioner identified other complaints of poor braking performance and low brake pedal received by NHTSA concerning Prius models. Broader review of the consumer complaints reported for all variants of the subject vehicle showed no indication that either the reported jolting sensation or the brake performance concerns reported are occurring in this vehicle population at a level that would require investigative action by NHTSA.The following recalls by Toyota were to address many of these complaints in Prius variants. Neither of these recalls is applicable to Ms. Powell?s 2012 Prius C: 1. Recall 10V-039 March 5, 2010 - 2010 Prius, Lexus HS - Reprogramming ABS ECU - Improve Antilock brake function over bumpy surfaces. 2. Recall 13V-235 August 7, 2013 - 2010 Prius, Lexus HS - Replace Brake Booster / Pump assembly - Low brake pedal due to nitrogen bubble in hydraulic portion of brake system. In the Agency?s view, additional investigation is unlikely to result in a finding that a defect related to motor vehicle safety exists in the subject vehicles.Therefore, given the need to allocate and prioritize NHTSA limited resources to best accomplish the Agency"s safety mission, the petition is denied.This action does not constitute a finding by NHTSA that a safety-related defect does not exist.The Agency will take further action if warranted by future circumstances.More details concerning our review can be found in the Federal Register Notice for this action.