One problem related to fail to accelerate has been reported for the 2010 Toyota Prius. The most recently reported issues are listed below.
Twice now my brand new 2010 Prius iv has failed to accelerate when I was driving. June 16 purchased the car. June 22 at a stop light on a surface street, continued on green light, car lost power in the intersection and I coasted to a stop. Restarted, and fine until August 3, 1443 miles on the car, when I stopped for gas, continued on to the highway, up to 65 mph, and car lost power again, would not accelerate, went down to 42 mph, and I coasted to the shoulder. Turned off power. Restarted, and fine again.