I recently purchased a 2009 Sierra Hybrid, 2WD truck. My initial impression is that this is a great vehicle. I have all of the standard features of a Sierra with gas mileage averaging 21 MPG combined City/Highway. Outstanding! Contrary to Expert reviews, I would not agree with assessments that transitions shifts between electric and gas as seamless. On the contrary, these transitions can be felt-- abruptly in some instances. I also have concerns regarding the transition between regenerative and hydraulic brakes. In some instances, my brakes have actually disengaged momentarily making me feel as though I might roll into the vehicle in front of me. A very uncomfortable feeling.
Just a quick update on my previous review. First, my problems with dis- engaging brakes and abrupt transmission shifts have been solved. The dealer where my Sierra Hybrid was sourced neglected to update my software. Updating software fixed the brake problem and a faulty transmission pump fixed the gear shifting problem. My Sierra now drives just like a standard Sierra and I'm a huge fan and I can confidently say that I would absolutely recommend this truck.
Cruise control doesn't work well if at all down hill. Tried Asking GM customer service VIA the phone about it. But the problem with this is, they just do not know and try to read the owners manual to you, Their is no information on how it works or even if it works in the owners manual. They are providing this support from their centers around World.. (One insisted Hydromantic meant Hybrid transmission). My Dodge manual - states clearly + or - 2 MPH down hill. I took it in to my dealer and said it doesn’t hold on any hill I drive (unlike all my other vehicles’. They said they can't fix it as their GM Tec paper states it may work or it may not, depending on the hill, and to down shift.