It's been awhile since I've driven our mega-mile Prius and it's everything I remembered. There's absolutely no steering feel. The ride is unrefined and the power is meager. In other words, it's about as far from a driver's car as modern vehicles get.
Knowing that, I'm not surprised that some Prius owners found their cars speeding beyond their control. They probably never really had control to begin with, they were just riding along.
Still, when I think back to the poor sap who said his Prius was "speeding down the freeway and he couldn't stop it" I just have to laugh. The Prius is so gutless it's hard to fathom the idea of it ever "getting out of control." The brakes are not great, but they are infinitely more powerful that the gas engine, the electric motor or any combination of the two. The idea that pushing on the brakes could not possibly overcome their propulsive force is just laughable.
Thankfully, the hysteria has died down and the incidents have seemingly vanished. Trust me, though, I wasn't the least bit worried from behind the wheel.
Ed Hellwig, Editor, Inside Line @ 84,988 miles

vt8919 says:
06:01 PM, 10/ 7/10
From what I've been told, all Priuses have had a brake override system from day one. So it's pretty amazing to hear people say their Prius couldn't stop even after hitting the brakes hard.
rickhamilton says:
05:38 PM, 10/ 9/10
@ vt8919: Yep, all Prii have had brake override since the first generation car. :)