I got a 2012 fwd 1lt 4 cylinder last November and love the vehicle except that I have noticed that whenever the nox is between 1500-2000 rpms while traveling down the highway, whenever I slightly step on the accelerator my entire vehicle gets a slight vibration and rumbling noise. It's enough of a vibration that it I can feel it a little bit in the seat and also on the gas pedal. It sort of tickles my foot, lol. It mainly occurs whenever I am going up small hills. Is anyone else experiencing this? It tends to do it more often with eco mode on.