drive by wire is not your enemy - diesels have been using DxW tech for quite awhile and if it was the tech that was a problem, then you would have been reading about run away diesels long ago. Don't hear about Ford, Dodge or GM trucks taking off like crazy for example.
The short answer is just bad design by Toyota.
my rant - maybe it is a bit of karma for being and idiot and buying the Prius in the first place - that car is for sheep and other followers, not those that choose to educate themselves. The battery in that car is an absolute "nickel nightmare" as I call it and just buying that car has done more damage to the environment than buying a turbo diesel car that is twice the size and comfortable. I am getting on my box now so I will slow my roll and leave with this; I am really interested in all of this type of tech and can say that battery is horrible, but don't believe all the hype including that BS Hummer "study" as it is rather full of crap and bias just like a Prius owner will bias his own opinion, but reality is nickel battery production is NASTY. So maybe just a bit of what comes around goes around
